Portland is the most populous city in the U.S. state of Maine and the seat of Cumberland County. Portland's population was 66,417 as of 2018. The Greater Portland metropolitan area is home to over half a million people, more than one-third of Maine's total population, making it the most populous metropolitan area in northern New England (an area comprising the states of Maine, New Hampshire, and Vermont) and the 106th-largest in the United States. Portland's economy relies mostly on the service sector and tourism. The Old Port district is known for its 19th-century architecture and nightlife. Marine industry still plays an important role in the city's economy, with an active waterfront that supports fishing and commercial shipping. The Port of Portland is the largest tonnage seaport in New England.