The routing from Pasadena to Los Angeles was west on Colorado Boulevard and then south on Figueroa Street.

The routing along Figueroa Street and the portion along Colorado Boulevard between Linda Vista Avenue and Figueroa Street also bore the designation of State Route 11. Business US 66 in San Bernardino, sometimes rendered "City" US 66 on contemporary maps, was a short business loop that existed in the city from the late 1940s until US 66 was decommissioned in California in 1964.

E Street continued on to become modern Kendall Drive, rejoining the US 66 mainline at Cajon Boulevard near Devore.

In 1959, the routing was truncated to Palm Avenue with the construction of the Barstow Freeway.

Business US 66 in Oklahoma City followed the older alignment of US 66 after the main route was moved to the interstates.

The original highway turned south from Edmond going into Oklahoma City, but the main route was moved onto Interstate 35.

At I-440/US 66, the Business US 66 designation ended; the main route (along with US 270) continued west on the 39th Expressway (now Oklahoma State Highway 66).

Business US 66 in Tulsa was an older alignment of US 66 that was redesignated when US 66 was moved to Interstate 44.

It turned south at Southwest Boulevard, rejoining the main route at I-44.

In the northern part of Joplin, US 66 headed on a zig-zag course towards the downtown area; Bypass US 66 continued south on Rangeline Road (then also U.S. Route 71, then turned west on Seventh Street (now Route 66).

A business route was created, following the older alignment through Carterville and continuing to downtown Webb City.

It was located on Kearney Street and West Bypass and, as the city expanded across it, was redesignated Business US 66 when that route was moved from downtown.

Non-special 66 continued west down, roughly, Interstate 270 to Lindbergh Boulevard, then south to rejoin the original alignment down Watson Road.

The business route turned south on Riverview, Broadway, Florissant Ave, Tucker Boulevard (then 12th Street), then southwest on Gravois Road, then west-southwest on Chippewa Street (which becomes Watson Road in the suburbs).

The road is now predominantly Illinois State Route 203, and (in East St. Louis) a city street.

It used 9th Street into Peoria Road to end at Dirksen Parkway north of Springfield.

Alternate US Highway 66 was designated in 1940 when a new alignment of Route 66 opened, passing through Plainfield, Illinois and bypassing Joliet.

The highway is now designated Illinois Route 53 after US 66 Alternate was eliminated in February 1967.