The West Bronx is that part of the New York City borough of the Bronx which lies west of the Bronx River; this roughly corresponds to the western half of the borough.
The West Bronx is more densely populated than the East Bronx, and is closer to Upper Manhattan. From the late 17th century to the middle 19th this was the central and southern part of the Town of Yonkers, but then became the separate Town of Kingsbridge. In 1874, the then towns of Kingsbridge, West Farms and Morrisania were transferred to New York County, becoming the first area outside Manhattan to be annexed by the City of New York. Today's West Bronx was then known as the "Annexed District." In 1898, the city annexed the modern-day East Bronx as well as western Queens County (today's borough of Queens), all of the City of Brooklyn (today's borough of Brooklyn), and all of Richmond County (today's borough of Staten Island to form the City of Greater New York. However, it was not until 1914 that the modern-day Bronx was actually named "the Bronx" after the river flowing from central Westchester and down the middle of the borough.
Physically, the western parts of the Bronx are hilly, dominated by a series of parallel ridges running south to north. The West Bronx has older tenement buildings, low income public housing complexes, multifamily homes in its lower income areas as well as larger single family homes in more affluent areas such as Riverdale. It includes New York City's fourth largest park: Van Cortlandt Park along the Westchester-Bronx border. The Grand Concourse, a wide ridgeline boulevard runs through it, north to south. Note that because the Bronx uses the same street numbering system as Manhattan, large portions of streets designated as "east" (e.g. East 161st Street) may actually be located west of the Bronx River. This is because the east-west divider is Fifth Avenue in Manhattan and Jerome Avenue in the Bronx, which is directly north of Fifth Avenue. Jerome Avenue was approximately the centerline of the original Annexed District, though not of the expanded modern Bronx.
