Websites listed below contain public infrastructure data. 
This list is not meant to be exhaustive; it lists the more commonly used and useful sites.
Energy
- Energy Information Administration - The Energy Information Administration (EIA) is a statistical agency of the U.S. Department of Energy. Find data under Sources and Uses, next by type. Most types will have a data tab.
Public Land
- Bureau of Land Management. Public Land Statistics - This website contains links to Public Land Statistics published by the Bureau of Land Management. Public Land Statistics provides annual reports on land and mineral uses, animal populations, recreational uses, and more.
Telecommunications
- Telecommunication Indicator Reports - The International Telecommunication Union's Telecommunication Indicator Reports present an analysis of trends and developments in the global telecommunications sector, backed by official statistics from the world's leading source of telecommunication information.
Traffic
- National Center for Statistics and Analysis - NCSA, an office of the National Highway Traffic Safety Administration, is responsible for providing a wide range of analytical and statistical support to NHTSA and the highway safety community at large.
Transportation
- National Transportation Safety Board - Charged with determining the probable cause of transportation accidents and promoting transportation safety, and assisting victims of transportation accidents and their families
- TranStats - The Bureau of Transportation Statistics (BTS) was established as a statistical agency in 1992. The Intermodal Surface Transportation Efficiency Act (ISTEA) of 1991 created BTS to administer data collection, analysis, and reporting.
- U.S. DOT Maritime Adm. - Programs of the Maritime Administration promote the development and maintenance of an adequate, well-balanced United States merchant marine, sufficient to carry the Nation's domestic waterborne commerce and a substantial portion of its waterborne foreign commerce, and capable of service as a naval and military auxiliary in time of war or national emergency.
Image source: Charles Bridge in Prague. Chosovi. CC BY-SA 2.5. Wikimedia Commons.
