It is approximately 160,000 miles (256,000 kilometers) of roadway important to the nation's economy, defense, and mobility. The National Highway System (NHS) includes the following subsystems of roadways:

• Interstate :The Eisenhower Interstate System of highways retains its separate identity within the NHS.
• Other Principal Arterials:These are highways in rural and urban areas which provide access between an arterial and a major port, airport, public transportation facility, or other intermodal transportation facility.
• Strategic Highway Network(STRAHNET): This is a network of highways which are important to the United States' strategic defense policy and which provide defense access, continuity and emergency capabilities for defense purposes.
• Major Strategic Highway Network Connectors: These are highways which provide access between major military installations and highways which are part of the Strategic Highway Network.
• Intermodal Connectors: These highways provide access between major intermodal facilities and the other four subsystems making up the National Highway System.
The National Highway System (NHS) includes the Interstate Highway System as well as other roads important to the nation's economy, defense, and mobility. The NHS was developed by the Department of Transportation (DOT) in cooperation with the states, local officials, and metropolitan planning organizations (MPOs).