During the planning stages US 30 was proposed to run through and terminate in Salt Lake City, Utah, but Idaho and Oregon objected. What is now US 30 through those states (west of Burley, Idaho) had been designated as part of U.S. Route 20, another transcontinental route, but it took a detour to the north through Yellowstone National Park, making it inaccessible during the winter season. The states agreed to take US 30 along that route, splitting from the route to Salt Lake City at Granger, Wyoming and running along what had been designated as U.S. Route 530 (US 530). (That number was then reused for the spur towards Salt Lake City.) The planned US 530 had ended at U.S. Route 91 at McCammon, Idaho, where the new US 30 turned north to Pocatello, meeting the planned US 20. (US 20 was truncated to Yellowstone but later extended along its own route to the Pacific Ocean.) What had been designated as U.S. Route 630 (US 630), from US 30 at Echo, Utah to Ogden, Utah, was to be extended east on former US 30 to US 30 at Granger and northwest on US 91 and what had been designated U.S. Route 191 to US 30 at Burley.