Tualatin Mountains

From Wikipedia, the free encyclopedia

The Tualatin Mountains (also known as the West Hills or Southwest Hills of Portland, Oregon) are a range of hills on the western border of Multnomah County, Oregon, USA. A spur of the Coast Range, they separate the Tualatin Basin of Washington County, Oregon from the Portland Basin of western Multnomah County, Oregon and Clark County, Washington. The hills date from the late Cenozoic era, and range up to over 1000 ft (305 m). Human settlement goes back 10,000 years to the area's earliest known residents, the Chinook people.

Despite steep slopes, periodic landslides, and multiple earthquake faults, many residences have been built in the Tualatin Mountains, though much the northern portion is undeveloped land within the 5,000 acre (20.23 km²) Forest Park. The landscape, inside and outside the park, is predominantly forested.

U.S. Highway 26 (the Sunset Highway) is the principle transportation link across the hills, travelling through a canyon and over the pass at Sylvan. This route through the hills connecting the agricultural Tualatin Basin to the navigable Willamette River was developed as a plank road in the 19th century, and was a major factor in the early growth of the city of Portland.

Since 1998, the Westside MAX light rail has run roughly parallel to US-26 through the hills, including a section tunneled deep underground.