Burlington is the most populous city in the U.S. state of Vermont and the seat of Chittenden County. It is located 45 miles south of the Canada–United States border and 94 miles south of Canada's second most populous municipality, Montreal. The city's population was 42,452 according to a 2015 U.S. census estimate. It is the least populous municipality in the United States to be the most populous incorporated area in a state.A regional college town, Burlington is home to the University of Vermont and Champlain College, a small private college. Vermont's largest hospital, the UVM Medical Center, is located within the city limits. The City of Burlington also owns the state of Vermont's largest airport, the Burlington International Airport, in neighboring South Burlington. In 2015, Burlington became the first city in the U.S. to run completely on renewable energy.