U.S. Highway 66 — popularly known as Route 66 — holds a special place in American consciousness. Its name commonly evokes images of simpler times, mom-and-pop businesses, and the icons of a mobile nation on the road. Travelers on Highway 66 today can easily experience this past, as many of the motels, gas stations, cafés, parks, trading posts, bridges, and roadbeds remain along the thoroughfare. These historic resources are reminders of our past and evidence of the origins of our current automobile-influenced society.

Route 66 embodies a complex, rich history that goes well beyond any chronicle of the road itself. An artery of transportation, an agent of social transformation, and a remnant of America’s past, it stretches 2,400 miles across two-thirds of the continent. The highway winds from the shores of Lake Michigan across the agricultural fields of Illinois, to the rolling hills of the Missouri Ozarks, through the mining towns of Kansas, across Oklahoma where the woodlands of the East meet the open plains of the West, to the open ranch lands of Texas, the enchanted mesa lands of New Mexico and Arizona, to the Mojave Desert, and finally to the “land of milk and honey” – the metropolis of Los Angeles and the shores of the Pacific Ocean. Flanked by historic buildings and diverse cultural resources, Route 66 slices across the continent, revealing the process of historical change that transformed the lives of people, their communities, and the nation. This fabled highway’s multiple alignments connect not only the East and the West, but also the past and the present.

Route 66 had its official beginnings in 1926 when the Bureau of Public Roads launched the nation’s first Federal highway system. Like other highways in the system, the path of Route 66 was a cobbling together of existing local, State, and national roads. The highway quickly became a popular route because of the active promotion of the U.S 66 Highway Association, which advertised it as “the shortest, best and most scenic route from Chicago through St. Louis to Los Angeles.


Merchants in small and large towns along the highway looked to Route 66 as an opportunity for attracting new revenue to their often rural and isolated communities. As the highway became busier, the roadbed received improvements, and the infrastructure of support businesses — especially those offering fuel, lodging, and food that lined its right of way — expanded. Even with tough times, the Depression that worked its baleful consequences on the nation produced an ironic effect along Route 66. The vast migration of destitute people fleeing their former homes actually increased traffic along the highway, providing commercial opportunities to a multitude of low capital, mom-and-pop businesses.

World War II caused a marked decline in civilian and tourist traffic, but it stimulated new business along U.S. 66, when it acted as a military transport corridor moving troops and supplies from one military reservation to another. Motels saw an increase in occupancy, as families of servicemen stationed at military bases stayed for long stretches. But more significantly, Route 66 facilitated perhaps the single greatest wartime mobilization, as thousands of jobseekers headed to California, Oregon, and Washington to work in defense plants.

When the war ended, traffic increased as rationing and travel restrictions were lifted. Automobile ownership grew dramatically over the next 10 years, with 52.1 million cars registered in 1955 (compared to the 25.8 million at the end of the war). With more cars and leisure time, families headed west on Route 66 to the Grand Canyon, Disneyland, and the beaches of Southern California.

With the heavier traffic, businesses along the highway boomed, and the image of Route 66 as a Dustbowl migration route changed to one of freedom and kicks. The bleak image of John Steinbeck's Grapes of Wrath faded as the upbeat lyrics of Bobby Troupe’s “Route 66” hit the airwaves. The adventures of two young men seeking their kicks in the 1960s television series, Route 66, further immortalized Route 66 as a highway of thrills.

Just as the enormous traffic in the decade after World War II sent Route 66 into a boom time, the popularity and crowding of the highway signaled its demise. In 1956, President Eisenhower, who had witnessed the military advantages of the German Autobahn during World War II, supported the passage of a law to construct a new system of high-speed, limited-access, four-lane divided highways — today’s interstates.

Five new interstates (I-55, I-44, I-40, I-15, and I-10) incrementally replaced U.S. 66 over the next three decades. Interstate construction coincided with the powerful forces of economic consolidation as evidenced by the growth of branded gasoline stations, motels, and restaurant chains. The 1984 bypassing of the last section of U.S. 66 by I-40 led to the official decommissioning of the highway in 1985, impacting countless businesses and communities along the road.


After Route 66’s decommissioning, members of public and private organizations and State and Federal agencies who understood the highway’s historical and social significance started campaigns to preserve and commemorate the road. New associations organized to promote travel and preservation of Route 66, working with State agencies to mark it with signs. Parts of Route 66 received new designations as State and/or National Scenic Byways. Businesses along the road again started to sell to tourists, who sought out the storied highway.

In 1990, the United States Congress passed Public Law 102-400, the Route 66 Study Act of 1990, recognizing that Route 66 had “become a symbol of the American people's heritage of travel and their legacy of seeking a better life." As a result of the law, the National Park Service conducted the Route 66 Special Resource Study to evaluate the significance of Route 66 and to identify options for its preservation, interpretation, and use. This study led to the enactment of Public Law 106-45 to preserve the cultural resources of the Route 66 corridor and to authorize the Secretary of the Interior to provide assistance. The law authorized the creation of the National Park Service Route 66 Corridor Preservation Program. This program provides financial and technical assistance to individuals; nonprofits; local, State, tribal and Federal agencies; and others to facilitate preservation of the most significant and representative historic resources along the route.

In 2008, the significance of Route 66 and the importance of preserving it were again recognized when the World Monuments Fund listed Route 66 on the Watch List of 100 Most Endangered Sites. The Watch calls international attention to threatened cultural sites around the world, and seeks to build capacities and constituencies for the long-term, sustainable protection of those sites. As a result of this listing, World Monuments Fund has partnered with American Express through its Sustainable Tourism Initiative to provide funding to support Route 66 projects, including an Economic Impact Study of Historic Preservation and Tourism, and this Route 66 National Park Service Discover Our Shared Heritage Travel Itinerary.

There is a spirit, a feeling that resides along this highway. The spirit of Route 66 lives in the people and their stories, the views and buildings, and travelers' perceptions of the highway. Today’s travelers can still experience a remarkable journey traveling through time on Route 66.

The Origins of Route 66 - Pre 1926

United States Highway 66 followed in the wake of the nation's first trans-Mississippi migration. In 1853, Congress commissioned Captain Amiel Weeks Whipple of the Army Topographical Corps to conduct a survey for a proposed transcontinental railroad. Congress ultimately opted against the railroad and instead subsidized a network of wagon roads to improve military and civilian communications throughout the western frontier. In 1857, Congress commissioned Lieutenant Edward Fitzgerald Beale to chart a wagon road following the 35th parallel from Fort Defiance close to the New Mexico/Arizona border to the Colorado River. Beale's Road established a vital military transportation and communication link between Fort Smith near the Arkansas River and the westernmost reaches of the Southwest. In underwriting the $200,000 expense to establish what Lt. Beale felt certain would become "the great emigrant road to California," the Federal Government provided the impetus for the creation of the transcontinental railroad and the establishment of Route 66.

Beale's Road was the frontier antecedent of Route 66. Interest in the route resurfaced under the National Old Trails Road Movement, when motorists began to discuss the need for an ocean-to-ocean thoroughfare in the first decades of the 20th century. Promoters hoped to capitalize on the national appeal of the Panama-Pacific Expositions scheduled to open in San Diego and San Francisco in 1915, as justification for Federal subsidies of a continuously paved transcontinental highway. As conceived in 1912, the National Old Trails Road was to originate on the east coast with branches to Baltimore and Washington, DC, and terminate on the west coast in San Diego. During its lifetime, the road's promotional arm, the National Old Trails Road Association, promoted improvement of the proposed ocean-to-ocean corridor as it retraced the nation's historic trails.  The association also championed good roads in America by advocating direct Federal involvement in road construction in lieu of Federal aid to State agencies. This concept became a part of Federal highway policy in 1916 that continues today.

The first leg of the ocean-to-ocean highway that the National Old Trails Association proposed in 1912 originated in Washington, DC and traced the Cumberland Road, a well-established historic avenue, to St. Louis. From Missouri, the highway followed the Santa Fe Trail to Albuquerque and Santa Fe before taking a more southerly course through Arizona to Flagstaff, gateway to the Grand Canyon. Flagstaff's pioneer lumberman, Matthew J. Riordan, detailed the final leg of the route that most closely approximates the 1927 orientation of U.S. Highway 66. Christened the "Grand Canyon Route," the road was eventually constructed from Williams to Ashfork and Seligman in Yavapai County to Topock, Arizona on the Colorado River, where automobiles could be loaded on railway flatcars and transported across an expansion bridge that the Santa Fe Railroad built to Needles, California. From this desert community, the road proceeded 164 miles across the Mojave to Barstow and the desert communities of Bakersfield and San Bernardino terminating in San Diego.

The official origin of Route 66 was the Federal Aid Highway Act of 1921. A road assessment of a decade earlier estimated the total mileage of rural roads in America at approximately 2.5 million miles, 10.5% of them surfaced. Of those 257,291 miles, only 32,180 had pavement of bituminous material, brick, or concrete. The intent of the Federal Aid Highway Act of 1921, successor to the earlier highway appropriations legislation of 1916, was to create a coherent highway network by requiring that Federal aid be concentrated on projects that would expedite completion of an adequate and connected system of interstate highways. A minimum of 60% of Federal funds were be spent on what was designated the primary or interstate network.

The automobile and construction of the vast network of highways that gave motorists a route to travel were both marvels of the 20th century.  Established to facilitate travel across the 3,000-mile stretch of mountains and prairies between New York and San Francisco, the Lincoln Highway predated Route 66 by more than a decade. From 1912 until the end of the First World War, cross-country travel along the Lincoln Highway was largely limited to the wealthy few who could afford an automobile and dared to challenge the uneven, ill-defined course of the road.  Route 66 opened the way for the masses to travel.

Route 66 was the result of America's infatuation with rapid mobility, mass transportation, and technological change. Historian Richard Davies wrote, “the automobile constituted a personalized urban mass transit system, allowing the owner to travel whenever or wherever he desired." Moreover, it provided a personal means of escape from the congestion of metropolitan America. One significant effect of the increased use of the automobile, according to Davies, was to reduce cross-country travel from an adventure of the affluent and stouthearted to a relatively inexpensive and common occurrence.

The 1920s were the first boom years for the automobile. In 1910, two years before the authorization of the Lincoln Highway, the United States had 180,000 registered automobiles, a ratio of about one car for every 5,000 citizens. The subsequent decade saw the addition of more than 17 million cars, trucks, and buses to America's motor fleet. This figure increased 6.5 times to 112 million in the 1970s. Not surprisingly, Americans demanded improved highways to serve the growing number of vehicles on America's roadways. The Federal Government's early response to these demands first breathed life into Route 66.

Although entrepreneurs Cyrus Avery of Tulsa, Oklahoma and John Woodruff of Springfield, Missouri deserve most of the credit for promoting the idea of an interregional link between Chicago and Los Angeles, their lobbying efforts were not successful until their dreams merged with the national program of highway and road development. While legislation for public highways first appeared in 1916 with revisions in 1921, it was not until Congress enacted a more comprehensive version of the law in 1925 that the government executed its plan for national highway construction. Officially, the Chicago-to-Los Angeles route received the numerical designation of Route 66 in the summer of 1926. That designation acknowledged the route as one of the nation's principal east-west arteries. Mostly, U.S. 66 was just an assignment of a number to an already existing network of State-managed roads, most of which were in poor condition.

From the outset, public road planners intended U.S. 66 to connect the main streets of rural and urban communities along its course for the most practical of reasons: most small towns had no prior access to a major national thoroughfare. Oklahoma achieved statehood in 1907, but before 1926, Cyrus Avery's hometown of Tulsa, and most of what was once called "Indian Territory," had few improved roads. In those days, driving the 103 miles of uneven dirt roads from Tulsa to Oklahoma City took six hours. Both admitted to the Union in 1912, scarcely 14 years before the construction of Route 66, New Mexico and Arizona suffered from the same lack of good roads.

Road use in these remote desert States was sporadic. In 1925, New Mexico's Office of the State Engineer reported that only an average of 207 cars used the road daily between Albuquerque and Gallup. Arizona reported a slightly higher daily count of 338 cars, but road conditions were not desirable. As described in the summer of 1925, the section between Ashfork and Seligman, Arizona was  "Unimproved except in the way of removing boulders from the road that might menace a low-clearance car . . . it is a twenty-mile (per hour) road." Extension of U.S. Highway 66 into these desolate western territories would help facilitate their transition to statehood by offering greater access to prospective residents and travelers.

Route 66 from 1926 - 1945

Formative Years: 1926-1932
Route 66 had its official beginnings in 1926 when the Bureau of Public Roads launched the nation’s first Federal highway system. Like other highways in the system, the path of Route 66 was a cobbling together of existing local, State, and national road networks. Extending 2,400 miles from Chicago to Los Angeles, the new highway wound through eight States and was not completely paved until 12 years after its designation. Many of the merchants in the small and large towns through which the highway passed looked to the road as an economic opportunity to bring much needed outside revenues into their often rural and isolated communities. Actively promoted in its early years, the highway quickly became a popular transcontinental route, because it offered a route with better weather than alternative east-west roadways. As the highway became busier with the nation’s traffic, the roadbed received marked improvements, and the infrastructure of support businesses, especially fuel, lodging, and food, lining its right-of-way expanded dramatically.

Spawned by the demands of a rapidly changing America, Route 66 did not follow a traditionally linear course in contrast to the Lincoln, the Dixie, and other highways of its day. Its diagonal route linked hundreds of predominantly rural communities in Illinois, Missouri, and Kansas to Chicago, thus enabling farmers to transport grain and produce for redistribution. This diagonal configuration was particularly significant to the trucking industry, which by 1930 rivaled the railroad for preeminence in the American shipping industry. In addition to its abbreviated route between Chicago and the Pacific coast, Route 66 traversed essentially flat prairie lands and enjoyed a more temperate climate than that of northern highways, further enhancing its appeal to truckers. The Illinois Motor Vehicles Division reported that between Chicago and St. Louis trucks increased from approximately 1,500 per day in 1931 to 7,500 trucks a day a decade later. Twenty-five percent of these were large tractor-truck, semi-trailer outfits.

Highway designers intended to make Route 66 "modern" in every sense of the term. State engineers worked to reduce the number of curves, widen lanes, and ensure all-weather capability. Until 1933, the responsibility for improving existing highways fell almost exclusively to individual States. The more assertive and financially prepared States met the challenge. Initial improvements cost State agencies an estimated $22,000 per mile. In 1929, Illinois boasted approximately 7,500 miles of paved roads, its entire portion of U.S. Highway 66. A Texaco Gasoline road report published that same year noted the route as entirely concrete in Kansas, 66% paved in Missouri, and 25% improved in Oklahoma. In contrast, the 1,200-mile western stretch had not seen a cement mixer, with the exception of California's metropolitan areas. Until the height of the Great Depression, Texas, New Mexico, Arizona, and the desert communities of southeast California had a collective total of only 64.1 miles of surfaced highway along Route 66.


The Great Depression and World War II: 1933--1945
Washington's increased level of commitment began with the Great Depression and the national appeal for emergency Federal relief measures. In his famous social commentary, The Grapes of Wrath, John Steinbeck proclaimed U.S. Highway 66 the "Mother Road." Steinbeck's classic 1939 novel and the 1940 film re-creation of the epic odyssey immortalized Route 66 in the American consciousness. An estimated 210,000 people migrated to California to escape the despair of the Dust Bowl. In the minds of those who endured that particularly painful experience and in the view of generations of children to whom they recounted their story, Route 66 symbolized the "road to opportunity."

Re-examining the Great Depression years, contemporary writers found that thousands of disillusioned immigrants returned home within months after reaching the Golden State. Of the more than 200,000 refugees who journeyed west to California beginning in the early 1930s, less than 16,000 people from the Dust Bowl proper ended up in California. Despite popular perceptions promoted in Steinbeck's novel, James Gregory argues convincingly that barely 8% of the "Dust Bowlers" who set out for California remained there. California's total demographic growth between 1930 and 1940 reflected scarcely more than a 22% increase, compared to a 53% growth rate in the following decade.

The importance of Route 66 to emigrating "Dust Bowlers" during the Depression years received wide publicity.  Less is known about the importance of the highway to those who opted to eke out a living in economically devastated Kansas, Oklahoma, West Texas, and New Mexico. During this time, U.S. Highway 66 and other major roads in America had integral links to President Roosevelt's revolutionary New Deal programs for work relief and economic recovery. Road improvements and maintenance work were central features of the New Deal's Civilian Conservation Corps (CCC) and Works Project Administration (WPA) programs. From 1933 to 1938, thousands of unemployed male youths from virtually every State were put to work as laborers on road gangs. Because of this monolithic effort, the entire highway from Chicago to Los Angeles had pavement by 1938. In Gregory’s final analysis, Route 66 affected more Americans on Federal work relief than people who used it during the famous exodus to California.

As the Depression worked its baleful effects on the nation, it also produced an ironic consequence along Route 66; the vast migration of destitute people fleeing from the privation of their former homes actually produced an increased volume of business along the highway, thus providing commercial opportunities for a multitude of low-capital, mom-and-pop businesses. The buildings constructed for these businesses reflected the independence of the operations, a general absence of standardization, and a decentralized economic structure. At the same time, it became clear that life along Highway 66 presented opportunities not available to the nearby towns and businesses that lost traffic to the important highway and who suffered accordingly. At a very early point it was evident that a major nearby highway could both bring business and take it away.

Completion of the all-weather capability of Route 66 on the eve of World War II was particularly significant to the nation's war effort. The experience of a young Army captain, Dwight D. Eisenhower, who found his command bogged down in spring mud near Fort Riley, Kansas while on a coast-to-coast maneuver, left an indelible impression. The War Department needed improved highways for rapid mobilization during wartime and for national defense during peacetime. At the outset of American involvement in World War II, the War Department singled out the West as ideal for military training bases, in part because of its geographic isolation and especially because it offered consistently dry weather for air and field maneuvers. The department invested over $230 million in new military bases in Arizona alone. Several military installations, including Fort Leonard Wood in Missouri, Fort Wingate Ordnance Depot in New Mexico, Navajo Ordnance Depot in Arizona, and Edwards Air Force Base in California, were established on or near Route 66.

America's mobilization for war after Pearl Harbor underscored the necessity for a systematic network of roads and highways. The War Department's expropriation of the nation's railways left a transportation vacuum in the West that only the trucking industry could fill. Automobile manufacturers suffered critical shortages of steel, glass, and rubber during the war years, and plants in Detroit converted to the production of tanks, aircraft engines, ordnance, and troop transports. According to one government source, the production of new cars dropped from 3.7 million in 1941 to 610 in 1943, because of rationing.

At the same time, production of trucks capable of hauling loads in excess of 30,000 pounds increased to keep pace with wartime demands. Studies by the Public Roads Administration between 1941 and 1943 showed that trucks rather than trains transported and delivered at least 50% of all defense-related material destined for America's war production plants. Because Route 66 was the shortest corridor between the west coast and the industrial heartland beyond Chicago, mile-long convoys commonly moved troops and supplies from one military reservation to another along the highway.

Route 66 helped to facilitate the single greatest wartime mobilization of labor in the history of the nation. Between 1941 and 1945, the government invested approximately $70 billion in capital projects throughout California, many in the Los Angeles-San Diego area. This enormous capital outlay underwrote entirely new industries that created thousands of civilian jobs. By 1942, with the exhaustion of available local labor in most areas on the Pacific Coast, war contractors began a frantic search for skilled and unskilled workers from across the United States. Under the provisions of the West Coast Manpower Plan initiated in September 1943, contractors prepared to offer jobs to 500,000 men and women to meet the production demands of global war.

In February 1942, Public Roads Administration Commissioner Thomas MacDonald announced that existing rail and bus transit facilities could accommodate only a small fraction of the 10 million workers required to operate the defense plants. The rest would have to move in private automobiles. They moved in unprecedented numbers. The net result of this mass migration was the loss of more than 1 million people from the metropolitan northeast between 1940 and 1943. Three Pacific Coast States--California, Oregon, and Washington--increased 38.9% in population (measured against a national average of 8.7%). Route 66 played a critical role in this vast movement of Americans to meet the demands of war.

The Post War Years
The social dislocation and uprooting of millions of Americans that began during the Great Depression and continued through World War II did not abate with the surrender of Germany and Japan. After the war, Americans were more mobile than ever before. Thousands of soldiers, sailors, and airmen who received military training in California, Arizona, New Mexico, Oklahoma, and Texas abandoned the harsh winters of Chicago, New York City, and Boston for the "barbecue culture" of the Southwest and the West. For many, Route 66 facilitated their relocation.

One such emigrant was Robert William Troup, Jr. of Harrisburg, Pennsylvania. Bobby Troup, former pianist with the Tommy Dorsey band and ex-Marine captain, penned a lyrical map of the now famous cross-country road. The words of his song, "get your kicks on Route 66," became the catch phrase for countless motorists, who moved back and forth between Chicago and the Pacific coast. One scholar likened the popular recording released in 1946 by Nat King Cole one week after Troup's arrival in Los Angeles to "a cartographic ballad." Bobby Troup's musical rendition provided a convenient mental road map for those who followed him west.

During the postwar decades, the population shift from "Snowbelt" to "Sunbelt" reached its zenith. Census figures for these years revealed population growth along Route 66 ranging from 40% in New Mexico to 74% in Arizona. Because of the great influx of people during the war years, California claimed over half of the total population of the West between 1950 and 1980.

The demographic disruption that began in the 1930s continued to stimulate roadside commerce. Storeowners, motel managers, and gas station attendants recognized early on that even the poorest travelers required food, automobile maintenance, and adequate lodging. Just as New Deal work relief programs provided employment with the construction and the maintenance of Route 66, the appearance of countless tourist courts, garages, and diners promised sustained economic growth after the road's completion. While military use of the highway during wartime ensured the early success of roadside businesses, the demands of the new tourism industry in the postwar decades gave rise to modern facilities that guaranteed long-term prosperity.

The roadside architecture along U.S. Highway 66 illustrates the evolution of these facilities. Most Americans who drove the route did not stay in hotels; they preferred accommodations more convenient for automobile travelers. Motels evolved from earlier features of the American roadside such as the auto camp and the tourist home. The auto camp developed as townspeople along Route 66 roped off spaces in which travelers could camp for the night. Camp supervisors, some employed by the various States, provided water, fuel wood, privies or flush toilets, showers, and laundry facilities free of charge. Camp Joy near Lebanon, Missouri and Red Arrow Campground in Thoreau, New Mexico are examples of auto camps that have survived to the present day. The successor to the auto camp was the tourist home, which provided many of the same amenities but with the added feature of indoor lodging in the event of inclement weather.


The natural outgrowth of the auto camp and tourist home was the cabin camp, sometimes called cottages, which offered minimal comfort at affordable prices. Many of these cottages are still in operation. Eventually, auto camps and cabin camps gave way to motor courts or motels with all of the rooms under a single roof. Motor courts offered additional amenities such as adjoining restaurants, souvenir shops, and swimming pools. An estimated 30,000 motor courts or motels were in operation along the nation's many highways in 1948. Some of the more famous still associated with Route 66 are the El Vado and the Zia Motor Lodge in Albuquerque, New Mexico and the Coral Court in St. Louis, Missouri.  The Wagon Wheel Motel in Cuba, Missouri; and Wigwam Village Motel #6 in Holbrook, Arizona still offer travelers the experience of what it was like to stop for the night on the Mother Road.

In the early years of Route 66, service station prototypes developed regionally through experimentation, then spread across the country. Gas stations had distinct buildings clearly associated with a particular petroleum company. Most started as simple house-like buildings with one or two service pumps in front and grew to larger, more elaborate stations complete with service bays and tire outlets. Soulsby's Shell Station in Mount Olive, Illinois and the Tower Fina Station in Shamrock, Texas are outstanding examples of the evolution of gas stations along Route 66.

Route 66 and many of the points of interest along the way were familiar landmarks by the time a new generation of postwar motorists hit the road in the 1960s. Many drew upon memories from excursions with their parents in the 1940s and 50s. World War II transformed the American public from a predominantly agricultural-industrial laboring class to an urban-technological society with increasing leisure and recreational time. American tourists' fondness for automobile travel and their enjoyment of sightseeing made them ideal targets for the service industries that cropped up along Route 66. A growing fascination with American Indian cultures led to increasing commercialization as public highways penetrated once inaccessible reservations. Interest in American Indians and the scenic, geologic, and historic wonders protected by the National Park System lured countless sightseers. To the average motorist during the post war period, a trip down Route 66 was an adventure through mainstream America accentuated by mom-and-pop motels, all-night diners, Indian curio shops, and far-too-infrequent restroom facilities. 

Demise and Resurgence of interest in Route 66
Excessive truck use during World War II and the comeback of the automobile industry immediately following the war brought great pressure to bear on America's highways. Automobile production jumped from just over 65,000 cars in 1945 to 3.9 million in 1948. Meanwhile, the deterioration of the national highway system was appalling. Virtually all roads, including Route 66, were functionally obsolete because of narrow pavements and antiquated structural features that reduced carrying capacity.

Emergency road building measures developed during wartime left bridges and culverts woefully inadequate for postwar needs. In the 1940s, most bridges in Illinois and Missouri used wood as a substitute for steel. Steel reinforcements were virtually nonexistent in concrete pavement, and sporadic maintenance left U.S. 66 and other highways riddled with potholes and gaping fissures.

The need for a modern system of national highways was painfully obvious. In 1941, Thomas MacDonald, director of the Public Roads Administration, told of the urgency for improved highways across the country in his report, "Highway for the National Defense." MacDonald estimated that 78,000 miles of roads and highways vital to the war effort needed improvements. The director estimated the cost for maintenance and repair to be $458 million. In anticipation of postwar traffic needs, MacDonald proposed a transcontinental expressway not to exceed 40,000 miles, designed to connect all of the major metropolitan centers in the United States. The Interregional Highway Committee, President Roosevelt's advisory group on national defense highways, adopted the so-called MacDonald Plan with the recommendation that $500 million be allocated over three years to implement the interstate highway system. National defense priorities during the war, however, tabled MacDonald's proposal until the surrender of Germany and Japan.

The Federal Aid Highway Act of 1944 incorporated both civilian and military highway needs into a single piece of legislation, the legal embodiment of the MacDonald Plan. The act incorporated the idea of a 40,000-mile national system of interstate highways, but Congress failed to appropriate funds for its construction. Not until the 1950s, and the War Department's prediction that the Korean Conflict was merely a prelude to a more widespread involvement in Asia, did the dream of an interstate system of expressways linking all regions of the United States become a reality.

Ironically, the public lobby for rapid mobility and improved highways that gained Route 66 its enormous popularity in earlier decades also signaled its demise beginning in the mid-1950s. Mass support for an interstate system of divided highways markedly increased during President Dwight D. Eisenhower's second term in the White House. General Eisenhower returned from Germany very impressed by the strategic value of Hitler's Autobahn. "During World War II," he recalled later, "I saw the superlative system of German national highways crossing that country and offering the possibility, often lacking in the United States, to drive with speed and safety at the same time." Heightened global tension hastened by the Cold War affirmed Eisenhower's resolve to improve the defense capabilities of the nation's highways.

Congress responded to the president's commitment by passing the Federal Aid Highway Act of 1956, which provided a comprehensive financial umbrella to underwrite the cost of the national interstate and defense highway system. In accord with the legislation, Interstate 40 west from Oklahoma City through the Texas Panhandle, New Mexico, northern Arizona, and finally ending in Barstow, California would replace the major segment of U.S. 66. By 1960, each of the States along the original U.S. 66 spent between $14 and $20 million to construct their portions of the interstate, designed to accommodate 1975 traffic projections. By 1970, two equally modern four-lane highways, Interstate 55 between Chicago and St. Louis and Interstate 44, which absorbed the old diagonal section from St. Louis to Oklahoma City, replaced the remaining segments of the original Route 66. On June 26, 1979, the American Association of State Highways and Transportation Officials (AASHTO) accepted the recommendation to eliminate the designation of Route 66. The committee noted that "U.S. 66 markings no longer served as a through-state guide to tourists, but in fact generated confusion because the route coincided with interstate designations over much of its length." Many of the States along this part of Route 66 pledged to preserve some symbol of the historic highway with signs reading "Old U.S. 66."

In many respects, the physical remains of Route 66 mirror the evolution of highway development in the United States from a rudimentary hodge-podge of State and county roads to a federally subsidized complex of uniform, well-designed interstate expressways. Various Route 66 alignments, many still detectable, illustrate the evolution of road engineering from coexistence with the surrounding landscape to domination of it. One outstanding example of the highway in its early form is the 3.5 mile section near Miami, Oklahoma, constructed between 1919 and 1924. Many of the original segments of Route 66 have been either abandoned or modified for secondary use.  Modern improvements such as widened shoulders, adequate swales, gentler curves, resurfaced pavement, and brightly painted safety stripes have not been able to keep the highway from becoming obsolete.

The last outdated, poorly maintained vestiges of U.S. Highway 66 succumbed to the interstate system in October 1984 when Interstate 40 at Williams, Arizona, replaced the final section of the original road. In 1985, the highway was officially decommissioned. Soon after, members of the public, private organizations, and local, State, and Federal agencies who understood the historic and social significance of the road began campaigns to preserve and commemorate the highway. As part of these efforts, many historic resources associated with Route 66 have been nominated and listed in the National Register of Historic Places. Numerous associations developed to promote travel and preservation of the road. State agencies worked to mark the road with signs so that the traveling public could remain aware of the route’s location. Some States designated Route 66 as a State and/or National Scenic Byway. Businesses along the road began catering to tourists who continued to seek out the alignments of the route.

In 1990, the United States Congress passed Public Law 101-400, the Route 66 Study Act of 1990, recognizing that Route 66 had “become a symbol of the American people's heritage of travel and their legacy of seeking a better life." In accord with the legislation, the National Park Service conducted the Route 66 Special Resource Study to evaluate the significance of Route 66 in American history and to identify options for its preservation, interpretation, and use. This study led to the enactment of Public Law 106-45 and the creation of the National Park Service Route 66 Corridor Preservation Program. This program provides financial and technical assistance to individuals; nonprofits; local, State, tribal and Federal agencies; and others to help preserve the most significant and representative historic resources along the route for people to learn from and enjoy.