Bureau of Transportation Statistics
Start here for transportation statistics.
Federal Aviation Administration.
National Transportation Safety Board.

Highway Statistics Series
Annual series of selected statistics relating to highway transportation.

National Center for Statistics and Analysis: Data
An office of the National Highway Traffic Safety Administration (NHTSA) and responsible for providing analytical and statistical support.

National Transportation Library
Contains thousands of full-text documents. The NTL is a repository of US Department of Transportation (DOT) information, serves as a portal for transportation data, and provides library services to US DOT employees.

Transport Research International Documentation (TRID)
Provides access to more than one million records of transportation research worldwide. Combines the Transportation Research Information Services (TRIS) and International Transport Research Documentation (ITRD) databases.

US Local and State Transportation Web Sites
APTA resource library has links to state and country transportation pages. Each state's page includes statewide, regional, and local transit systems and transportation providers, state government transportation agencies, and other statewide, regional, and local transportation web sites.