The Transportation Systems Sector-a sector that comprises all modes of transportation (Aviation, Maritime, Mass Transit, Highway, Freight Rail, and Pipeline)-is a vast, open, interdependent networked system that moves millions of passengers and millions of tons of goods. The transportation network is critical to the Nation's way of life and economic vitality. Ensuring its security is the mission charged to all sector partners, including government (Federal, State, regional, local, and tribal) and private industry stakeholders. Every day, the transportation network connects cities, manufacturers, and retailers, moving large volumes of goods and individuals through a complex network of approximately 4 million miles of roads and highways, more than 100,000 miles of rail, 600,000 bridges, more than 300 tunnels and numerous sea ports, 2 million miles of pipeline, 500,000 train stations, and 500 public-use airports.