near the eastern edge of the Crazy Mountains to Harlowton, where US 191 is briefly concurrent with US 12. North of Harlowton, US 191 is concurrent with Montana Highway 3 for , to Eddie's Corner. US 191 proceeds eastward from Eddie's Corner to Lewistown, on a roadway shared with US 87 and Montana 200, in a wrong-way concurrency. US 191 reaches the Canada–US border after going through Lewistown, across the Missouri River at the Charles M. Russell National Wildlife Refuge, and through Malta. It ends at the international border at Port Morgan, and the road continues into Saskatchewan as Highway 4 toward Swift Current. History Background The routing of US 191 has drastically changed through the years having been extended and shortened several times. The original route designated in 1926 ran from Idaho Falls, Idaho, to West Yellowstone, Montana along the route now numbered U.S. Route 20. West Yellowstone is the only town that has been continuously served by the highway since its commissioning. On February 1, 1935, US 191 was extended over Montana Highway 187 (also known as the Gallatin Way) to Bozeman, Montana. As US 191 has mostly been extended while US 91 has largely been truncated, US 191 is now ten times longer than its parent. At one time US 191 connected to its parent, US 91, twice: at Idaho Falls, Idaho and Brigham City, Utah. Today the highway does not connect to its parent, or even enter Idaho. In Utah, there have been 2 completely different iterations of U.S. 191 serving different areas of the state. The original iteration is now State Route 13, which is mostly a frontage road for Interstate 15. In this alignment, the route in between Idaho Falls and the Utah line also paralleled I-15. 1981 extension By 1981, due to the construction of Interstate 15 and extension of other U.S. Highway designations, US 191 had been truncated to a route between West Yellowstone and Malta, Montana. Utah and Wyoming lobbied AASHTO to create a single highway that would connect several National Parks in their states to facilitate tourism. The initial proposal was to extend U.S. Route 163 north into Wyoming. However it was later decided to add Arizona to this proposal for a new highway and instead extend US 191 south. Most of the southern extension recycled existing U.S. and state highways. However, some new sections were constructed. When the 1981