The Eastside of the King County, Washington area in the United States is a collective term for the suburbs of Seattle located on the east side of Lake Washington.

Seattle is a seaport city on the West Coast of the United States. It is the seat of King County, Washington. With a 2022 population of 749,256 it is the most populous city in both the state of Washington and the Pacific Northwest region of North America, and the 18th-most populous city in the United States. The Seattle metropolitan area's population is 4.02 million, making it the 15th-largest in the United States. Its growth rate of 21.1% between 2010 and 2020 made it one of the country's fastest-growing large cities.