Boston, officially the City of Boston, is the capital and most populous city of the Commonwealth of Massachusetts in the United States and 21st most populous city in the country. The city proper covers 48.4 square miles (125 km2) with an estimated population of 692,600 in 2019, also making it the most populous city in New England. It is the seat of Suffolk County (although the county government was disbanded on July 1, 1999). The flag of Boston consists of a sky blue field and the seal of the city of Boston, Massachusetts, in the center. The flag is sometimes flown in a darker shade of blue, more of a turquoise. It was designed in 1913 and adopted by the Boston City Council on January 29, 1917. Full HD.