Willamina is a city in Polk and Yamhill Counties in the U.S. state of Oregon. Take a look below for 15 great and fascinating facts about Willamina, Oregon, United States. 1. The population was 2,025 at the 2010 census. 2. The Yamhill County portion of Willamina is part of the Portland–Vancouver–Beaverton, Metropolitan Statistical Area, while…