Pasco is one of three cities that make up the Tri-Cities region of the state of Washington. The Tri-Cities is a mid-sized metropolitan area of approximately 256,000 people that also includes the cities of Kennewick and Richland. The population was 54,600 at the 2010 census. Since that time the city has experienced rapid growth, and the official April 1, 2011 estimate from the Washington State Office of Financial Management puts the city's population at 61,100.