<P> By the late 1960s, most of the rural sections of US 66 had been replaced by I - 40 across New Mexico with the most notable exception being the 40 - mile (64 km) strip from the Texas border at Glenrio west through San Jon to Tucumcari, which was becoming increasingly treacherous due to heavier and heavier traffic on the narrow two - lane highway . During 1968 and 1969, this section of US 66 was often referred to by locals and travelers as "Slaughter Lane" due to numerous injury and fatal accidents on this stretch . Local and area business and civic leaders and news media called upon state and federal highway officials to get I - 40 built through the area; however, disputes over proposed highway routing in the vicinity of San Jon held up construction plans for several years as federal officials proposed that I - 40 run some five to six miles (8 to 10 km) north of that city while local and state officials insisted on following a proposed route that touched the northern city limits of San Jon . In November 1969, a truce was reached when federal highway officials agreed to build the I - 40 route just outside the city, therefore providing local businesses dependent on highway traffic easy access to and from the expressway via the north--south highway that crossed old US 66 in San Jon . I - 40 was completed from Glenrio to the east side of San Jon in 1976 and extended west to Tucumcari in 1981, including the bypasses around both cities . </P> <P> Originally, highway officials planned for the last section of US 66 to be bypassed by interstates in Texas, but as was the case in many places, lawsuits held up construction of the new interstates . The US Highway 66 Association had become a voice for the people who feared the loss of their businesses . Since the interstates only provided access via ramps at interchanges, travellers could not pull directly off a highway into a business . At first, plans were laid out to allow mainly national chains to be placed in interstate medians . Such lawsuits effectively prevented this on all but toll roads . Some towns in Missouri threatened to sue the state if the US 66 designation was removed from the road, though lawsuits never materialized . Several businesses were well known to be on US 66, and fear of losing the number resulted in the state of Missouri officially requesting the designation "Interstate 66" for the St. Louis to Oklahoma City section of the route, but it was denied . In 1984, Arizona also saw its final stretch of highway decommissioned with the completion of I - 40 just north of Williams, Arizona . Finally, with decertification of the highway by the American Association of State Highway and Transportation Officials the following year, US 66 officially ceased to exist . </P> <P> With the decommissioning of US 66, no single interstate route was designated to replace it . I - 55 covered the section from Chicago to St. Louis; I - 44 carried the traffic on to Oklahoma City; I - 40 took the largest chunk, replacing 66 to Barstow, California; I - 15 took over for the route to San Bernardino; and I - 210 and State Route 2 (SR 2) or I - 10 carried the traffic of US 66 across the Los Angeles metropolitan area to Santa Monica, and the seashore . </P> <P> When the highway was decommissioned, sections of the road were disposed of in various ways . Within many cities, the route became a "business loop" for the interstate . Some sections became state roads, local roads, private drives, or were abandoned completely . Although it is no longer possible to drive US 66 uninterrupted all the way from Chicago to Los Angeles, much of the original route and alternate alignments are still drivable with careful planning . Some stretches are quite well preserved, including one between Springfield, Missouri, and Tulsa, Oklahoma . Some sections of US 66 still retain their historic 9 - foot - wide (2.7 m) "sidewalk highway" form, never having been resurfaced to make them into full - width highways . These old sections have a single, paved lane, concrete curbs to mark the edge of the lane, and gravel shoulders for passing . </P>

Where does route 66 start and end map