This polyline shapefile depicts the National Highway Planning Network, a comprehensive network database of the United States' major highway system. It consists of the highways comprised of Rural Arterials, Urban Principal Arterials and all National Highway System routes. The data set covers the 48 contiguous States plus the District of Columbia, Alaska, Hawaii, and Puerto Rico. The nominal scale of the data set is 1:100,000 with a maximal positional error of ±80 meters. This layer is part of the 2014 National Transportation Atlas Database. The National Transportation Atlas Databases 2014 (NTAD2014) is a set of nationwide geographic datasets of transportation facilities, transportation networks, associated infrastructure and other political and administrative entities. These datasets include spatial information for transportation modal networks and intermodal terminals, as well as the re¬lated attribute information for these features. This data supports research, analysis, and decision-making across all transportation modes. It is most useful at the national level, but has major applications at regional, state and local scales throughout the transportation community. The data used to compile NTAD2014 was provided by our partners within the United States Department of Transportation (USDOT) and by other agencies throughout the United States Federal Government. These contributors are the actual data stewards and are ultimately responsible for the maintenance and accuracy of their data. The National Highway Planning Network (NHPN) is a geospatial network database that contains line features representing just over 450,000 miles of highways in the United States. The NHPN contains geospatially referenced information on the National Highway System (NHS), the Eisenhower Interstate System, the Strategic Highway Network (STRAHNET) and NHS Intermodal Connectors. In addition to the NHS, the NHPN covers all roads functionally classified as principal arterial and rural minor arterial. The primary purpose of this geospatial data set is to serve the Federal Highway Administration (FHWA) needs in highway planning, policy analysis, visualization of the Highway Performance Monitoring System (HPMS) database and network modeling. The NHPN is the digital source used for coding and publishing the FHWA approved National Highway System maps.
