 When State Route 155 was first established in 1964, U.S. Route 97 passed through downtown Omak and Okanogan on what is now State Route 215, rather than on its easterly bypass as it does today.Thus, State Route 155 continued west on what is now State Route 155 Spur to terminate at U.S. Route 97 in downtown Omak.When the US 97 bypass was built a few years later, State Route 155 was rerouted onto its current alignment.