Conventionally, the area east of Wissahickon Creek, which comprises Germantown, Mount Airy, Chestnut Hill, and Cedarbrook, is termed the 'Upper Northwest', and the area west of the creek, which comprises Roxborough, Wissahickon, East Falls, and Manayunk, is termed the 'Lower Northwest'.

In some places the buildings and street grid have existed for three centuries, other spots nearby were farmland until after World War II, and have infrastructure that is very recently developed, 18th-century farmhouses to 19th-century rowhouses to 20th-century shopping centers.

From an enclave of working-class Germantown rowhouses and small single mansions to the wealthy estates of Chestnut Hill, both may have been built in the period of 1880-1920.

This hilly terrain is a distinct characteristic of Manayunk and Roxborough, making them popular for any recreation that can use a good hill (such as sledding and soapbox derbies, or especially challenging sessions of running and biking).

Upper Roxborough, because it is one of the highest elevations in Philadelphia, is the site of a reservoir and many of the city's broadcast transmission towers.