Boston (pronounced i//) is the capital and largest city of the state of Massachusetts (officially the Commonwealth of Massachusetts), in the United States. Boston also serves as county seat of Suffolk County. The largest city in New England, the city proper, covering 48 square miles (124 km2), had an estimated population of 636,000 in 2012, making it the 21st largest city in the United States. The city is the anchor of a substantially larger metropolitan area called Greater Boston, home to 4.5 million people and the tenth-largest metropolitan area in the country. Greater Boston as a commuting region is home to 7.6 million people, making it the sixth-largest Combined Statistical Area in the United States.