National Highway System, Intermodal Connectors, and Principal Arterials: 2018
Figure

Notes:
NHS = National Highway System or the interstate highway system; STRAHNET = Strategic Highway Network or a network of highways that are important to the U.S. strategic defense policy. MAP-21 principal arterials = those rural and urban roads serving major population
centers not already categorized above.
Description:
This map is included in the Transportation Statistics Annual Report 2020 publication.
Source:
U.S. Department of Transportation (USDOT), Federal Highway Administration, Highway Performance Monitoring System, as cited in USDOT, Bureau of Transportation Statistics, National Transportation Atlas Database, available at www.bts.gov as of September 2018.