The following sites provide information on specific historic roads or regional systems and histories in the United States and abroad.

National/Transcontinental
http://www.lincolnhighwayassoc.org
Lincoln Highway Association

http://www.national66.com/
National Route 66 Federation

http://www.yellowstonetrail.org/
Yellowstone Trail, “From Plymouth Rock to Puget Sound”

http://marylandnationalroad.org/
Historic National Road, Maryland

http://www.nationalroadpa.org/
Historic National Road, Pennsylvania

http://www.wvcommerce.org/travel/gettinghere/wvbyways/nationalroad.aspx
Historic National Road, West Virginia

http://www.ohionationalroad.org/
Historic National Road, Ohio

http://www.indiananationalroad.org/
Historic National Road, Indiana

http://www.nationalroad.org/
Historic National Road, Illinois

Eastern United States
http://www.bostonroads.com/
Information regarding roads in metro Boston

http://merrittparkway.org/
Merritt Parkway Conservancy

http://www.phillyroads.com/
Information regarding road in metro Philadelphia

Central United States
http://www.ci.chi.il.us/Transportation/lsd/history.html
South Lake Shore Drive, Chicago, history

Southern United States
http://www.dixiehighway.org/
The Dixie Highway

Western United States
http://www.milepost.com/home
History of the Alaska Highway

http://www.columbiariverhighway.com
Historic Columbia River Highway, Oregon

http://www.oregon.gov/ODOT/HWY/HCRH/
Historic Columbia River Highway, Oregon Department of Transportation

http://www.arroyoseco.org/asparkway.htm
Arroyo Seco Parkway, Los Angeles to Pasadena

International
The following sites provide information on historic roads throughout the world.

http://www.ess.uci.edu/~oliver/silk.html
The Silk Road (Asia)