Somerville is a city located directly to the northwest of Boston, in Middlesex County, Massachusetts, United States. As of 2010, the United States Census has the city with a total population of 75,754 people, and is the most densely populated municipality in New England. As of 2010, it was the 16th most densely populated incorporated municipality in the country. Somerville was established as a town in 1842, when it was separated from Charlestown.