The Department of Homeland Security and the Department of Transportation are designated as the Co-Sector-Specific Agencies for the Transportation Systems Sector. The nation's transportation system quickly, safely, and securely moves people and goods through the country and overseas.
The Transportation Systems Sector consists of seven key subsectors, or modes:
- Aviation includes aircraft, air traffic control systems, and approximately 450 commercial airports and 19,000 additional airports, heliports, and landing strips. This mode includes civil and joint use military airports, heliports, short takeoff and landing ports, and seaplane bases
- Highway Infrastructure and Motor Carrier encompasses nearly 4 million miles of roadway, almost 600,000 bridges, and some 400 tunnels in 35 states. Vehicles include automobiles, motorcycles, trucks carrying hazardous materials, other commercial freight vehicles, motorcoaches, and school buses
- Maritime Transportation System consists of about 95,000 miles of coastline, 361 ports, 25,000 miles of waterways, 3.4 million square miles of Exclusive Economic Zone, and intermodal landside connections, which allow the various modes of transportation to move people and goods to, from, and on the water
- Mass Transit and Passenger Rail includes service by buses, rail transit (commuter rail, heavy rail--also known as subways or metros--and light rail, including trolleys and streetcars), long-distance rail--namely Amtrak and Alaska Railroad--and other, less common types of service (cable cars, inclined planes, funiculars, and automated guideway systems)
- Pipeline Systems consist of vast networks of pipeline that traverse hundreds of thousands of miles throughout the country, carrying nearly all of the nation's natural gas and about 65 percent of hazardous liquids, as well as various chemicals. These include approximately 2.2 million miles of natural gas distribution pipelines, about 168,900 miles of hazardous liquid pipelines, and more than 109 liquefied natural gas processing and storage facilities
- Freight Rail consists of seven major carriers, hundreds of smaller railroads, over 140,000 miles of active railroad, over 1.3 million freight cars, and roughly 20,000 locomotives. Further, over 12,000 trains operate daily. The Department of Defense has designated 30,000 miles of track and structure as critical to mobilization and resupply of U.S. forces.
- Postal and Shipping moves over 574 million messages, products, and financial transactions each day. Postal and shipping activity is differentiated from general cargo operations by its focus on letter or flat mail, publications, or small- and medium-size packages and by service from millions of senders to nearly 152 million destinations.