Mattapan was annexed to Boston in 1870 as part of Dorchester. Like other neighborhoods of the time, Mattapan developed as the railroads and streetcars made downtown Boston accessible. Predominately residential, Mattapan is home to a mix of single homes as well as two and three family houses. Mattapan Square, where Blue Hill Avenue, River Street, and Cummins Highway meet, is the commercial heart of the neighborhood.