T he capital of Massachusetts , Boston is the largest city in the New England area of the United States , the 23rd biggest city in the country . Despite covering only 90 square miles , its 685,094 inhabitants make it one of the most densely populated areas in the United States , with a density of 13,841 people per square mile , according to World Population . The Greater Boston area is the fourth most densely populated region in the United States , only behind the New York Metro Area , Greater Los Angeles and the South Florida Metro Area . The population of Boston is affected heavily by the day-night cycle . Findings by World Population place 1.2mn people within the city limits during work hours and 2.0mn people in the city for special events . Due to its participation in several important historical events , Boston has a year-round tourism industry . One of the top 10 tourist attractions in the US , according to City Date , the city features almost 2,000 restaurants and 62 historical sites .