Seattle is a major coastal seaport city and the seat of King County, in the U.S. state of Washington. With an estimated 634,535 residents as of 2012, Seattle is the largest city in the Pacific Northwest region of North America and is one of the fastest-growing cities in the nation. The Seattle metropolitan area of around 4 million inhabitants is the 15th largest metropolitan area in the United States. The city is situated on a narrow isthmus between Puget Sound (an inlet of the Pacific Ocean) and Lake Washington, about 100 miles (160 km) south of the Canada–United States border. A major gateway for trade with Asia, Seattle is the 8th largest port in the United States and 9th largest in North America in terms of container handling.