Historic U.S. Route 66 had been completely paved by 1938.
When the highway was established in 1926, many sections were dirt, gravel, or only partly improved. Paving projects continued through the 1930s as federal and state governments upgraded the road and connected rural communities to the national highway system.
The completion of paving was especially important during the Great Depression. Public works programs, including projects associated with the Works Progress Administration, helped improve roads while providing employment. Better surfaces made long-distance travel more reliable for motorists, commercial vehicles, and migrants.
Complete paving did not freeze Route 66 in its final form. Engineers continued to straighten curves, replace bridges, bypass town centers, and build wider alignments. Consequently, travelers today may find several historic versions of the road in the same region. The 1938 date refers to paving completion, not the end of Route 66 construction or realignment.