Monroe is a city in Snohomish County, Washington, United States. It is located at the confluence of the Skykomish, Snohomish, and Snoqualmie rivers near the Cascade foothills, about 30 miles northeast of Seattle. Monroe's population was 19,699 as of the 2020 census. Monroe was originally founded in 1864 as the town of Park Place, located at the river confluence among several existing settlements in the Tualco Valley.