United States

Traffic Counts - List of Average Daily Traffic (ADT) tallies for major metropolitan areas.
http://www.webspawner.com/users/beachbuminda650/

Southern Highroads Trail - A designated scenic highway going through Georgia, Tennessee, North Carolina and South Carolina. Official tourism site.
http://southernhighroads.org/

Green Highways Partnership - Multi-sector initiative that seeks to incorporate environmental sustainability into all surface transportation infrastructure. FAQs, media resources, and contact information.
http://www.greenhighways.org/

Interstate-Guide.com - Includes the Interstate Guide, the List of Interstate Business Routes, and the Interstate Shield Gallery. Includes coverage.
http://www.interstate-guide.com/

U.S. Hwy. 90 - The Southern Route 66 - Travelogue and old postcard scans. Page linked is Louisiana but there are also pages on Texas, Mississippi, Alabama, and Florida.
http://ucmmuseum.com/hwy90la.htm

Road Trip USA - Great detail on various at-grade long-distance routes.
http://www.roadtripusa.com/

CatSynth.com - Highways - Contains commentary and information about various routes across the country.
http://www.ptank.com/catsynth/static.php?page=highways

Coast to Coast on US 50 - History and other information.
http://www.route50.com/

American Highway Users Alliance - Interest group representing motor vehicle users and businesses promoting highway safety and efficiency. News updates and Rules of the Road publication information.
http://www.highways.org/

Larry's Phat Page - Highways - Route logs of and personal travel comments about various highways, primarily Interstates.
http://www.phatpage.org/highways.html

US Highways: From US 1 to US 830 - Complete list including historic, plus other features.
http://www.us-highways.com/

Multiplex Index - Gallery of shields along roads with more than one route number.
http://www.m-plex.com/roads/mpindex.html

U.S. Code of Federal Regulations Title 23 - Highways - Complete contents of the 2005 revision.
http://www.access.gpo.gov/cgi-bin/cfrassemble.cgi?title=200523

Bygone Byways - Descriptions of current and former US routes 66, 80, 99, and 101 as well as other notes.
http://www.bygonebyways.com/

Midwestroads.com - Covers the respective region of the country. Includes historic maps, planning documents and reports, and photos.
http://www.midwestroads.com/

U.S. Route 6 Tourist Association - Covers the entirety of the route. Page includes background, news articles, and maps.
http://www.route6tour.com/

High Priority Corridors - Information about these highways which have been set aside as most important in the 1998 bill "Transportation Equity Act for the 21st Century (TEA-21)".
http://www.aaroads.com/high-priority/

Summer of 6 - Weblog of a 2006 trip documenting U.S. 6 in comments and photographs.
http://www.floodgap.com/roadgap/6/

Appalachian Regional Commission Development Corridors - Unofficial site which explains these potential thoroughfares.
http://www.aaroads.com/arc/

The ZZYZX Interstate Highway List - Gives an overview of the system and provides a listing of all one- and two-digit routes.
http://www.ihoz.com/interstates.html

Redhighways.com - Text guides to various U.S. Highways, with links.
http://www.redhighways.com/

Highway Deficiencies - A compendium of substandard features.
http://www.ajfroggie.com/roads/deficiency/

US Route 20 - Information and some history.
http://www.usroute20.com/

American Society of Highway Engineers - Newsletters, FAQ, and other features relevant to the trade.
http://www.highwayengineers.org/

MotorcycleRoads.US - Compilation of lists specifically for motorcyclists who prefer scenic or winding routes.
http://www.motorcycleroads.us/

SmarTraveler - Traffic reports for cities and other travel information.
http://www.smartraveler.com/

Expressways Online - Commentary and articles about relevant issues, authored by a former editor of Roads and Bridges magazine.
http://www.expresswaysonline.com/

AARoads Roadtrips - Contains photographic logs of various routes in the East-Central region.
http://www.aaroadtrips.com/

US Highway 101: Guide to the Pacific Coast Highway - Covers many aspects.
http://www.us-101.com/

American Byways - Covers Kentucky, Ohio Tennessee, Virginia, and West Virginia and surrounding areas. Photography, historical information, and forum.
http://www.americanbyways.com/

Adopt A Highway Maintenance Corporation - Provides for sponsorship in various states.
http://www.adoptahighway.com/

Road Geek Stuff - Includes various topics.
http://www.mylandofmisery.com/roads.htm

Route 40 - National Road - Guide to the first federally-funded road in the U.S. (1800s) and the route which followed it later (US 40).
http://www.route40.net/

United States Code Title 23 - Highways - Complete contents of the document.
http://www.access.gpo.gov/uscode/title23/title23.html

The Interstate is 50 - American Association of State Highway and Transportation Officials page commemorating the 50th anniversary of the Interstate System in 2006. Includes history and photographs.
http://www.interstate50th.org/

American Association of State Highway and Transportation Officials - Much information on this consortium.
http://www.transportation.org/

National Cooperative Highway Research Program - Details on this division of the Transportation Research Board, a unit of the National Research Council.
http://www.trb.org/CRP/NCHRP/NCHRP.asp

Highways and Gas Stations - Includes information on various highways in Minnesota, Missouri, Ohio, and Pennsylvania.
http://www.geocities.com/pennsylvaniatpk7689/

Roads, Highways and Trails - Detailed personal travelogue.
http://rachela.tripod.com/roads/roads.html

Heartland Expressway - A proposed divided highway running between Rapid City, South Dakota and Denver, Colorado, also known as High Priority Corridor 14 of the Intermodal Surface Transportation Efficiency Act of 1991. Maps, project status, and various other facts.
http://www.heartlandexpressway.com/

Gorp's Top Ten US Scenic Drives - List which includes details on the Blue Ridge Parkway, Seward Highway, California 1, Vermont 100, and the Custer Scenic Byway.
http://gorp.away.com/gorp/activity/byway/topten.htm

USroadman.com - Log of travels along U.S.-numbered routes. Includes route histories and links to photographs.
http://home.att.net/~usroadman2/

3-digit Interstate Highways - Location, history, and trivia. Includes ones that were proposed but never built.
http://www.kurumi.com/roads/3di/

The Road Information Program - Nonprofit organization promoting policies which are designed to improve traffic conditions.
http://www.tripnet.org/

Kim Russell's U.S. Highways Page - Gives brief descriptions of all U.S.-numbered routes, past and present, as well as suggestions for possible future routings.
http://www.geocities.com/kimrussell72/

Corporate Sponsor Adopt A Highway Program - Lists the steps which may be taken for Adopt-A-Highway Litter Removal Service of America, Incorporated to manage the section which is requested. Includes option to receive visual impressions.
http://www.adoptahighway.net/

Ports-to-Plains Trade Corridor - Coalition to improve north-south transport in the West-Central part of the country. Maps, construction information, and contact information.
http://www.portstoplains.com/

Highway History - Federal Highway Administration page with a collection of articles including those on U.S. Highway numbering and creation of the Interstate system.
http://www.fhwa.dot.gov/infrastructure/history.htm

Highways.TV - Links to state transportation resources throughout the country including weather, cams, reports, and hotel reservations.
http://www.highways.tv/

Michelle Skinner's Interstate Page - Gives descriptions of each route.
http://www.geocities.com/michelleskinnerfreeway/

Roadsidephotos.sabr.org - Contains information about certain highways culled from cross-country trips. Includes maps.
http://roadsidephotos.sabr.org/

US Road Conditions.com - Gives links to each state's respective webpages.
http://www.usroadconditions.com/

Southern Highways - Various scenes from along the southern tier of the country.
http://www.angelfire.com/ms3/corridorx/

3dis that Aren't--State Route Spurs and Loops - Information about state routes that could be an interstate of the same number.
http://members.tripod.com/~chris295/

Road Stuff - Much Northeast coverage. Also includes photos, map scans, and a log of Route 9's in the country.
http://neilbert.com/blog/