re-designated Topock–Kingman–Ash Fork Highway and the Ash Fork–Flagstaff–Winslow–Holbrook Highway west of Holbrook. East of Holbrook, the original route through Springerville became the Holbrook–Springerville–New Mexico State Line Highway, while the recently constructed new route through Lupton became the Holbrook–Lupton Highway. U.S. Highway designation Across the country, the numerous named auto trails began creating problems for motorists. Many auto trails had confusing alternate routes and were not always the most direct routes; also, multiple different auto trails often overlapped on the same roadway. During the annual meeting of the American Association of State Highway Officials (AASHO) in San Francisco, California, in 1924, Minnesota state maintenance engineer A.H. Hinkle lobbied the organization to reorganize the nation's transcontinental highway system, suggesting a nationwide numbering system of well-located and direct interstate highways be implemented. AASHO agreed to Hinkle's ideas, passing a resolution on November 20, 1924, to develop a better organized interstate highway system. AASHO then sent a recommendation to the Secretary of Agriculture Howard M. Gore to create a joint board between the Bureau of Public Roads and state highway officials from across the nation to develop a new organized system of numbered interstate highways. Gore acted on the recommendation in 1925, establishing the Joint Board on Interstate Highways. After intensive discussion, debating, and planning, the Joint Board submitted a mostly finalized proposal to the new Secretary of Agriculture, William M. Jardine, on October 26, 1925. The new system would use signs in the form of a white shield with black outlines, displaying the name of the state in which the highway was traveling through, the letters "U.S." to symbolize the highway system being an interstate numbering system rather than a regional state system, and the number of the route below the letters "U.S." on the shield. The highways would also be numbered in an organized fashion with the highest numbers being in the northeastern United States and lowest being in the southwest. Even-numbered routes would travel east to west while odd-numbered routes would travel north to south. The major north–south routes would end with the number "1" as the last digit, while major transcontinental east–west routes would utilize the number "0" as the last digit. This proposed system would come to be known as the United States Numbered Highway System. Among the new proposed highways was a roughly crescent-shaped route named U.S. Route 60 (US 60). US 60 would run from Los Angeles,