Marysville is a city in Snohomish County, Washington, United States, part of the Seattle metropolitan area. The city is located 35 miles (56 km) north of Seattle, adjacent to Everett on the north side of the Snohomish River delta. It is the second-largest city in Snohomish County after Everett, with a population of 70,714 at the time of the 2020 U.S. census. As of 2015, Marysville was also the fastest-growing city in Washington state, growing at an annual rate of 2.5 percent.