Maps related to Southeastern Pennsylvania Physical Relief Map of Pennsylvania revealing the Piedmont Plateau (Southeastern PA) area in the lower right section that is bordered by the Appalachian Mountains (showing an S-like shape as they span from the bottom left-central part of the state to its upper right corner.) Pennsylvania Land Use Notice the different pattern for the Southeast PA area conforming to the physical pattersn shown above. Pennsylvania Sub Regions   South/East Pennsylvania Autumn Foliage Zone 3 Pennsylvania Trout Season Map with a different seasonal date for the "18 southeastern" counties. Pennsylvania Regions Approved Trout Waters SEPTA Region Map i.e., the Southeastern Penna. Transportation Authority        Southeastern Pennsylvania RC&D Logo for the Resource Conservation & Development Council Pennsylvania Tourism Regions Philadelphia and the Countryside area highlighted.

Southeastern Pennsylvania is part of the rolling Piedmont region containing the foothills of the Appalachian Mountains which border the region.  It is also a sub-region in the greater Mid-Atlantic (Middle Atlantic) region. It has some of the best farmland in the state. The area is identified as a separate climate division called Pennsylvania Southeastern Piedmont by the NOAA. 

While the name, "Southeastern Pennsylvania", can be slightly shortened to Southeast Pennsylvania (or Southeastern PA or even Southeast PA), Southeastern Pennsylvania (or Southeastern PA) is the more common usage, however you will also see the shortened name of Southeast PA used for convenience.


Delaware Valley and the Greater Philadelphia Metropolitan Region

Pennsylvanians that are Philadelphia City centric, tend to think in terms of Greater Philadelphia, while those in the surrounding suburbs and outer areas tend to think more in terms of the Delaware Valley, with Philadelphia a part of it.  

The Greater Philadelphia Region (or District or Market Area) also extends into South Jersey and Northern Delaware (also called the "Tri-State area").

Delaware Valley includes not just Pennsylvania, but counties in Southern NJ and Northern DE  (i.e., the Tri-State area), and Cecil County, MD if you go for it's broadest use.

Pennsylvanians often use the terms interchangeably (Greater Philadelphia = Delaware Valley = Southeastern Pennsylvania) when talking casually. And depending on where you live, they can have overlapping meaning, but they are not the same. 

Since Pennsylvania is such a large state, you have to know the context and the viewing perspective when a region within PA is discussed.


So What IS the Southeastern Pennsylvania Region?

Depending on your point of view, Southeastern Pennsylvania is made up of as few as 3 counties (Chester, Delaware and Philadelphia counties, sometimes referred to as the Southeast "corner" of the state) to as many as 18, with the most common understanding that it is made up of at least 5 counties (which make up the PA side of the greater Delaware Valley):

 
If using the shortened form of Southeast PA, most will almost always be referring to Philadelphia and it's surrounding counties (5), with possibly all or portions of the outer row of Lancaster, Berks, Lehigh and Northampton counties (and occasionally Lebanon and Schuylkill counties).  


If you combine the 13 county Pennsylvania Highlands region and the overlapping 10 county Pennsylvania Dutch Country region, with the PA side of the Delaware Valley region, throwing in the bordering Juniata and Schuylkill counties, you will have the 18 county region known officially in some departments at the state level as the greater Southeastern Pennsylvania region:


18 County Southeastern Pennsylvania including Juniata County

The Pennsylvania Highlands area is part of the Appalachian Mountains and has many ecological features including large wooded areas, is also subdivided into two overlapping (Lehigh County is included in both) regions: Pennsylvania Dutch County and the Lehigh Valley Region (Lehigh and Northampton counties).

Rarely, unless it's being viewed at the state level, do most people consider all 18 counties to be Southeastern Pennsylvania.  From my experience it's more common for people to be referring to the immediate 5-county area (or sometimes adding the outer counties to the 5: Berks, Lancaster, Lehigh, Northampton.)



Note: To make things a little more "interesting", Southeastern, PA is also a USPS post office address that is used for mail drops. It is located in Chester County.




See also: Pennsylvania Fast Facts




County Map of Pennsylvania

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