Brookline is a town in Norfolk County, Massachusetts, in the United States, and is a part of Greater Boston. Brookline borders six of Boston's neighborhoods: Brighton, Allston, Fenway-Kenmore, Mission Hill, Jamaica Plain, and West Roxbury. The city of Newton lies to the west of Brookline. At the 2010 census, the population of the town was 58,732. Brookline was first settled in 1638 as a hamlet in Boston, but was incorporated as a separate town in 1705.
According to the U.S. Census Bureau, Brookline has a total area of 6.8 sq mi (17.7 km2), all but 0.039 sq mi (0.1 km2) (0.44%) of which is land. The northern part of Brookline, roughly north of the D-line tracks, is urban in character, as highly walkable and transit rich. The population density of this part of town is nearly 20,000 inhabitants per square mile (8,000 /km2), on a par with the densest neighborhoods in nearby Cambridge, Somerville and Chelsea, Massachusetts (the densest cities in New England), and just below that of central Boston's residential districts (Back Bay, South End, Fenway, etc.). The overall density of Brookline, which also includes suburban districts and grand estates south of the D-line, is still higher than that of many of the largest cities in the United States, especially in the South and West. Brookline borders Newton (part of Middlesex County) to the west and Boston (part of Suffolk County) in all other directions; it is therefore non-contiguous with any other part of Norfolk County. Brookline became an exclave in 1873, when the neighboring town of West Roxbury was annexed by Boston (and left Norfolk County to join Suffolk County), and Brookline refused to be annexed by Boston after the Brookline-Boston annexation debate of 1873. Brookline separates the bulk of the city of Boston (except for a narrow neck or corridor near the Charles River) from its westernmost neighborhoods of Allston-Brighton, which had been the separate town of Brighton until annexed by Boston in 1873.
As of the census of 2010, there were 58,732 people, 24,891 households, and 12,233 families residing in the town. The population density was 8,701.0 people per square mile (3,247.3/km≤). There were 26,448 housing units at an average density of 3,889.6 per square mile (1,501.9/km≤).
Image: "Intersection of Harvard and Beacon Streets, Coolidge Corner, Brookline, MA" by Ddogas - Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons.