Germantown, Philadelphia
Germantown stretches for about two miles along Germantown Avenue northwest from Windrim and Roberts Avenues. Germantown has been consistently bounded on the southwest by Wissahickon Avenue, on the southeast by Roberts Avenue, and on the east by Wister Street and Stenton Avenue, but its northwest border has expanded and contracted over the years. When first incorporated as a borough in 1689, Germantown was separated from the rural Germantown Township by Washington Lane; later, the border was expanded to Carpenter and East Gorgas Lanes; it was then rolled back to Washington Lane in 1846, and remained there until the borough was absorbed into the city of Philadelphia in 1854.
Today, the western part of the former borough is the neighborhood known simply as 'Germantown' (though is sometimes called 'West Germantown') and the eastern part is the neighborhood of 'East Germantown'. While the boundary between the two neighborhoods is not well-defined and has varied over time, these days 'Germantown' usually refers to the part of the former borough that lies west of Germantown Avenue, up through West Johnson Street, and 'East Germantown' to the part that lies east of Germantown Avenue, up through East Upsal Street.
Mount Airy, Philadelphia
There is no official boundary between Mount Airy and Germantown. The most common consensus is that Johnson Street is the de facto boundary; however, the West Mount Airy Neighbors and East Mount Airy Neighbors organizations consider Washington Lane to be Mount Airy's southern edge. The question is moot, however, as the two neighborhoods blend together very gradually. Historically, the entire area was part of the German Township. Many buildings in Mount Airy carry the identity and even the name of Germantown in one way or another. For example, the Unitarian Society of Germantown, the Germantown Jewish Centre, the Germantown Christian Assembly, and the Germantown Montessori School are all in Mount Airy, yet also belong culturally to Germantown. Parts of the Battle of Germantown in 1777 occurred throughout Mount Airy. The special relationship linking the two has its roots in the time before the Act of Consolidation, when Germantown was a borough separate from the City of Philadelphia, and its rural environs were what is now Mount Airy.