Chelsea is a city in Suffolk County, Massachusetts, United States, directly across the Mystic River from the city of Boston. As of 2013, Chelsea had an estimated population of 36,828. It is also the second most densely populated city in Massachusetts behind Somerville. With a total area of just 2.21 square miles, Chelsea is the smallest city in Massachusetts in terms of total area.Chelsea is a diverse, working-class community that contains a high level of industrial activity. It is one of only three Massachusetts cities in which the majority of the population identifies as Hispanic or Latino, alongside Lawrence and Holyoke. After flirting with bankruptcy in the 1990s, the once-struggling industrial city has reversed a prolonged decline and in recent years has enjoyed sustained economic growth.