Auburn is a city in King County, Washington, United States (with a small portion crossing into neighboring Pierce County). The population was 70,180 at the 2010 United States Census. Auburn is a suburb in the Seattle metropolitan area, and is currently ranked as the 15th largest city in the state of Washington. Auburn is bordered by the cities of Federal Way, Pacific, and Algona to the west, Sumner to the south, Kent to the north, and unincorporated King County to the east. The Muckleshoot Indian Reservation lies to the south and southeast.

Kent is a city in King County, Washington, United States. It is part of the Seattle–Tacoma–Bellevue metropolitan area and had an estimated population of 132,319 as of 2019, making it the fourth-largest municipality in greater Seattle and the sixth-largest in Washington state. The city is connected to Seattle, Bellevue and Tacoma via State Route 167 and Interstate 5, Sounder commuter rail, and commuter buses. Incorporated in 1890, Kent is the second-oldest incorporated city in King County, after Seattle. It is generally divided into three areas: West Hill (mixed residential and commercial along Interstate 5), Valley (primarily industrial and commercial with some medium density residential; significant parkland along Green River), and East Hill (primarily residential with retail).

Tacoma ( tə-KOH-mə) 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 miles (51 km) southwest of Seattle (of which it is the largest satellite city), 31 miles (50 km) northeast of the state capital, Olympia, and 58 miles (93 km) northwest of Mount Rainier National Park. The population was 191,704, 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. Tacoma adopted its name after the nearby Mount Rainier, originally and locally called Takhoma or Tahoma. It is locally known as the "City of Destiny" because the area was chosen to be the western terminus of the Northern Pacific Railroad in the late 19th century. The decision of the railroad was influenced by Tacoma's neighboring deep-water harbor, Commencement Bay. By connecting the bay with the railroad, Tacoma's motto became "When rails meet sails". Commencement Bay serves the Port of Tacoma, a center of international trade on the Pacific Coast and Washington's largest port. The city gained notoriety in 1940 for the collapse of the Tacoma Narrows Bridge, which earned the nickname "Galloping Gertie". Like most industrial cities, Tacoma suffered a prolonged decline in the mid-20th century as a result of suburbanization and divestment. Since the 1990s, downtown Tacoma has experienced a period of revitalization. Developments in the downtown include the University of Washington Tacoma; Line T (formerly Tacoma Link), the first modern electric light rail service in the state; the state's highest density of art and history museums; and a restored urban waterfront, the Thea Foss Waterway.

Burien ( BEWR-ee-ən) is a suburban city in King County, Washington, United States, located south of Seattle on Puget Sound. As of the 2010 Census, Burien's population was 33,313, which is a 49.7% increase since incorporation in 1993. An annexation in 2010 increased the city's population significantly, and as of 2019 the population was an estimated 51,500.