Settlement and borders
Once part of Algonquian territory, Brookline was first settled by European colonists in the early 17th century. The area was an outlying part of the colonial settlement of Boston and known as the hamlet of Muddy River. In 1705, it was incorporated as the independent town of Brookline. The northern and southern borders of the town were marked by two small rivers or brooks, hence the name. The northern border with Brighton (which was itself part of Cambridge until 1807) was Smelt Brook. (That name appears on maps starting at least as early as 1852, but sometime between 1888 and 1925 the brook was covered over.) The southern boundary, abutting Boston, was the Muddy River.
The Town of Brighton was merged with Boston in 1874, and the Boston-Brookline border was redrawn to connect the new Back Bay neighborhood with Allston-Brighton. This created a narrow strip of land along the Charles River belonging to Boston, cutting Brookline off from the shoreline. It also put certain lands north of the Muddy River on the Boston side, including what are now Kenmore Square and Packard's Corner. The current northern border follows Commonwealth Avenue, and on the northeast, St. Mary's Street. When the Emerald Necklace of parks and parkways was designed for Boston by Frederick Law Olmsted in the 1890s, the Muddy River was integrated into the Riverway and Olmsted Park, creating parkland accessible by both Boston and Brookline residents.
Throughout its history, Brookline has resisted being annexed by Boston, in particular during the Brookline-Boston annexation debate of 1873. The neighboring towns of West Roxbury and Hyde Park connected Brookline to the rest of Norfolk County until they were annexed by Boston in 1874 and 1912, respectively, putting them in Suffolk County. Brookline is now separated from the remainder of Norfolk County.
Brookline has long been regarded as a pleasant and verdant environment. In 1841 edition of the Theory and Practice of Landscape Gardening, Andrew Jackson Downing described the area this way:
The town has since seen considerable development, though still does maintain a considerable amount of greenspace in certain neighborhoods.
Transportation and economy
Two branches of upper Boston Post Road, established in the 1670s, passed through Brookline. Brookline Village was the original center of retail activity. In 1810, the Boston and Worcester Turnpike, now Massachusetts Route 9, was laid out, starting on Huntington Avenue in Boston and passing through the village center on its way west.
Steam railroads came to Brookline in the middle of the 19th century. The Boston and Worcester Railroad was constructed in the early 1830s, and passed through Brookline near the Charles River. The rail line is still in active use, now paralleled by the Massachusetts Turnpike. The Highland Branch of the Boston and Albany Railroad was built from Kenmore Square to Brookline Village in 1847, and was extended into Newton in 1852. In the late 1950s, this would become the Green Line "D" Branch.
The portion of Beacon Street west of Kenmore Square was laid out in 1850. Streetcar tracks were laid above ground on Beacon Street in 1888, from Coolidge Corner to Massachusetts Avenue in Boston, via Kenmore Square. In 1889, they were electrified and extended over the Brighton border at Cleveland Circle. They would eventually become the Green Line "C" Branch.
Thanks to the Boston Elevated Railway system, this upgrade from horse-drawn carriage to electric trolleys occurred on many major streets all over the region, and made transportation into downtown Boston faster and cheaper. Much of Brookline was developed into a streetcar suburb, with large brick apartment buildings sprouting up along the new streetcar lines.