U.S.HIGHWAYS/INTERSTATES

Origins of the U.S. Numbered Highway System
http://www.fhwa.dot.gov/infrastructure/numbers.cfm

Old National Highways and Trails
http://www.marion.ohio-state.edu/fac/schul/trails/national/natlist.html

Single and Two StateTrails
http://www.marion.ohio-state.edu/fac/schul/trails/state/statelist.html

Interstate Numbers
http://www.ihoz.com/basic.html

U.S. Scenic Byways
http://byways.org

DOT- Department of Transportation
http://www.fhwa.dot.gov/

Federal Highway Administration (FHWA)
http://www.fhwa.dot.gov

National Highway Traffic Safety Administration (NHTSA)
http://www.nhtsa.dot.gov/