United States Federal Highway Administration page with a collection of various auto trail, U.S. highway, and Interstates histories, some from older FHWA publications, as well as other related information.

Includes information about the El Camino Real de Tierra Adentro National Historic Trail, which traverses the country of Mexico and the U.S. state of New Mexico.

Detailed information about trail from Oregon to Missouri.

Guide to the old highway along the northern tier of the United States.

Site covering the routing in Oregon, U.S. along the river in the general location of modern US 30 and Interstate 84. Includes activity information, pictures, postcards and ephemera scans.

Early plans for systems in the United States, some implemented, some not.

Covers that state's portion of the road from Illinois to Maryland, U.S. Includes history and attraction listing.

Structure built over I-80 in Nebraska, U.S., commemorating the old wagon trail. Virtual tour included.

Guide to the first federally-funded road in the U.S. (1800s) and the route which followed it later (US 40).

A gold-rush trail cutting through the hunting grounds of the Northern Plains Indians in Montana and Wyoming, U.S.