National Network
National Network (NN). The composite of the individual network of highways from each State on which vehicles authorized by the provisions of the STAA are allowed to operate. The network in each State includes the Interstate System, exclusive of those portions excepted under 658.11 or deleted under 658.11(d), and those portions of the Federal-aid Primary System in existence on June 1, 1991, set out by the FHWA in appendix A to this part.