Tacoma is a mid-sized urban port city and the county seat of Pierce County, Washington, United States. The city is on Washington's Puget Sound, 32 mi southwest of Seattle (of which it is the largest satellite city), 31 mi northeast of the state capital, Olympia, and 58 mi northwest of Mount Rainier National Park. The population was 198,397, according to the 2010 census. Tacoma is the second-largest city in the Puget Sound area and the third-largest in the state. Tacoma also serves as the center of business activity for the South Sound region, which has a population of around 1 million.