State D.O.T.'s

US Department of Transportation

• http://www.dot.gov/

PHMSA (Pipeline and Hazardous Materials Safety Administration)

• http://www.phmsa.dot.gov/

FHWA (Federal Highway Administration)

• http://www.fhwa.dot.gov/index.html

Turner Fairbank Highway Research Center

• http://www.tfhrc.gov/

Alabama

•  Alabama Department of Transportation
  

Alaska

• Alaska Dept. of Transportation and Public Facilities

Arizona

• Arizona Dept. of Transportation

Arkansas

• Arkansas Highway and Transportation Department (AHTD)
  

California

• California Dept. of Transportation

Colorado

• Colorado Department of Transportation
  

Connecticut

• Connecticut Advanced Pavement Lab
  

Delaware

• Delaware Department of Transportation
  

District of Columbia

• District of Columbia Department of Transportation
  

Florida

• Florida Dept. of Transportation

Georgia

• Georgia Dept. of Transportation

Hawaii

• Hawaii Dept. of Transportation

Idaho

• Idaho Transportation Dept.

Illinois

• Illinois Dept. of Transportation

Indiana

• Indiana Department of Transportation

Iowa

• Iowa Dept. of Transportation

Kansas

• Kansas Dept. of Transportation

Kentucky

• Kentucky Dept. of Transportation

Louisiana

• Louisiana Dept. of Transportation and Development
• Louisiana Transportation Research Center

Maine

• Maine Dept. of Transportation

Maryland

• Maryland Dept. of Transportation
• Maryland State Highway Administration
  

Massachusetts

• Massachusetts Executive Office of Transportation and Construction 
• Mass Highway Department
  

Michigan

• Michigan Dept. of Transportation

Minnesota

• Minnesota Dept. of Transportation

Mississippi

• Mississippi Department of Transportation
  

Missouri

• Missouri Department of Transportation
  

Montana

• Montana Department of Transportation
  

Nebraska

• Nebraska Department of Roads
  

Nevada

• Nevada Department of Transportation
  

New Hampshire

• New Hampshire Department of Transportation
  

New Jersey

• New Jersey Dept. of Transportation
• New Jersey Port Authority of New York and New Jersey
  

New Mexico

• New Mexico Highway and Transportation Department
  

New York

• New York State Dept. of Transportation
• New York Port Authority of New York and New Jersey
• Thruway Authority, New York State
  

North Carolina

• North Carolina Dept. of Transportation
• North Carolina Division of Highways
• ITRE: UNC Institute for Transportation Research and Education
  

North Dakota

• North Dakota Dept. of Transportation

Ohio

• Ohio Dept. of Transportation

Oklahoma

• Oklahoma Dept. of Transportation

Oregon

• Oregon Dept. of Transportation Web Server

Pennsylvania

• Pennsylvania Department of Transportation 
• Penn State Center for Intelligent Transportation Systems
  

Puerto Rico

• Department of Transportation and Public Works
  

Rhode Island

• Rhode Island Dept. of Transportation

South Carolina

• South Carolina Department of Transportation
  

South Dakota

• South Dakota Dept. of Transportation

Tennessee

• Tennessee Dept. of Transportation

Texas

• Texas Dept. of Transportation
• Texas Center for Transportation Research
• Texas Transportation Institute
  

Utah

• Utah Department of Transportation
  

Vermont

• Vermont Agency of Transportation
  

Virginia

• Virginia Dept. of Transportation
• Virginia Dept. of Aviation
• Virginia Tech Transportation Infrastructure & System Engineering Division
  

• Washington Department of Transportation

West Virginia

• West Virginia Dept. of Transportation

Wisconsin

• Wisconsin Dept. of Transportation

• Wyoming Department of Transportation