Historical Geography

During it's early history, France, Connecticut, Maryland, New York, and Virginia laid claim to portions of Pennsylvania. French claims to western Pennsylvania were resolved by the French and Indian War (1754-63).

Claimant Details
Connecticut Considered all of Pennsylvania north of the 41 degree parallel theirs - according to a charter from Charles II in 1662.
Maryland Claimed that portion of Pennsylvania south of the 40 degree parallel except the southwestern section claimed by Virginia. This dispute was resolved peaceably by the 1767 Mason-Dixon Survey.
New York The boundary at the 42nd parallel was finalized in 1787.
Virginia Virginia claimed the southwestern portion of Pennsylvania that included Allegheny, Beaver, Fayette, Greene, Washington, and Westmoreland counties. The current boundary for this area was settled in 1784.

Modern Geography

If you need to find a specific place in the US or in other parts of the world, there are some excellent resources available online now. The best place to start for local or US place names is the U.S. Geological Survey where you can use their online search engine to locate any place or feature in the USA.