Transportation Data, GIS & Modeling

National Highway System Routes – Washington State

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 Federal Department of Transportation in 1995 in cooperation with the states, local officials, and metropolitan planning organizations (MPOs). There have been only minor changes to the NHS until the Moving Ahead for Progress in the 21st Century Act (MAP-21) was authorized by congress and signed into law in 2012. MAP-21 resulted in the addition of 1,200 miles of Washington roads to the NHS.

The NHS consists of NHS routes, Intermodal Facilities, and intermodal connector routes where required for travel from the NHS routes to the Intermodal Facilities. Routes designated as Strategic Highway Network (STRAHNET) by the Department of Defense also form part of the NHS.

Washington NHS routes are maintained in Washington’s Highway Performance Monitoring System (HPMS) and represented in Washington’s HPMS spatial network (GIS). Changes and updates to the NHS are reported to FHWA annually.


NHS Documents

Washington 2016 State Highway NHS List (pdf 1.0 mb)    Washington 2016 Local Agency NHS List(pdf 1.0 mb)



Changes to Washington’s NHS

Changes to the NHS must meet the federal guidance criteria detailed in US Code, Title 23 Part 470 Highway Systems (see link below) and involve WSDOT, affected local and regional officials and MPO’s and the FHWA WA Division Office. Formal approval of changes to the NHS is issued by the FHWA Office of Planning. Changes to Washington’s approved NHS are managed by the WSDOT HPMS Section.

FHWA Guidance Criteria for modifications to the NHS

FHWA re-issued Guidance related to the FAST Act

Contact: Heath Bright
Phone: 360-570-2370

National Highway System (NHS) Map

View the current National Highway System routes below, or for use in another program download the data from the WSDOT GeoData Distribution Catalog under Transportation Features.

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