Who numbered the Interstates?
Following enactment of the Federal-Aid Highway Act of 1956, officials of the U.S. Bureau of Public Roads (BPR) and the American Association of State Highway Officials (AASHO) agreed that AASHO should apply numbers to the Interstate System, as it did to the U.S. numbered highways. In fact, the numbering plan for U.S. numbered highways was the model for the Interstate System—but in mirror image (for example, U.S. 1 is on the East Coast, while I-5 is on the West Coast; U.S. 10 is in the north while I-10 is in the south). With basic guidelines in hand, AASHO’s Executive Secretary, A. E. “Alf” Johnson, applied numbers to the Interstate map. His handiwork was approved by AASHO’s Route Numbering Subcommittee and Executive Committee and adopted by the BPR in September 1957. Because the States own the Interstates, cooperation with AASHO (and its successor, the American Association of State Highway and Transportation Officials [AASHTO]) in the numbering of Interstates has continued. However, und
