Monmouth, Oregon, is located in Polk County, part of the Willamette Valley region in the western part of the state. The city is approximately 15 miles west of Salem and 65 miles south of Portland. Monmouth is close to several other cities in the area, including Independence and Dallas. The city is also within easy driving distance of other popular destinations in the region, such as the Oregon Coast, Silver Falls State Park, and the Cascade Mountains. Monmouth's central location in Polk County makes it an excellent starting point for exploring the surrounding natural beauty and nearby cities.