Penn wanted Philadelphia, meaning "love brotherly", to be a place where religious tolerance and the freedom to worship were ensured. Philadelphia's name is shared with an ancient city in Asia Minor mentioned by the Bible's Book of Revelation. It was William Penn's desire, as a Quaker, that his "Holy Experiment" would be found blameless at the Last Judgment.
When established, Philadelphia County consisted mainly of the area from the Delaware River west between the Schuylkill River to the south and the border with Bucks County to the north; the western boundary was undefined. Two counties would be formed out of Philadelphia County, Berks County which was formed during 1752 (from parts of Chester, Lancaster, and Philadelphia counties), and Montgomery County established during 1784. From these separations, as well as other border changes, was created the present-day boundaries of the county.
The City of Philadelphia, as planned by Penn, comprised only that portion of the present day city situated between South and Vine Streets and the Delaware and Schuylkill Rivers. Other settlements were made beyond the boundaries of the city, and in the course of time they became incorporated separately and had separate governments.
Several of these settlements were situated immediately contiguous to the "city proper" of Philadelphia, such as Southwark and Moyamensing in the south, the Northern Liberties District, Kensington, Spring Garden and Penn District to the north, and West Philadelphia and Blockley to the west — which combined with the City of Philadelphia formed practically one continuously urban area, the whole group being known abroad simply as Philadelphia.
Bucks County (northeast)
Burlington County, New Jersey (east)
Camden County, New Jersey (southeast)
Gloucester County, New Jersey (south)
Delaware County (southwest)
Montgomery County (northwest)