This map displays the National Highway System (NHS) in Washington State.  The NHS is comprised of State Highways and Local Agency roads. This dataset is used as a general reference layer for geographic information systems at the Washington State Department of Transportation. The National Highway System consists of roadways important to the nation's economy, defense, and mobility. This web map was created for use in the WSDOT NHS website. If you have any questions about this data, please contact Heath Bright, HPMS/Functional Class Supervisor - heath.bright@wsdot.wa.gov - (360) 570-2370. If you're having trouble viewing these services, please contact our Online Map Support.The National Highway System (NHS) includes the following subsystems of roadways (note that a specific highway route may be on more than one subsystem):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 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).