In the Pennsylvania statutes, counties are referred to in terms of their "class". A class is a classification based on population size. The state uses data from the U.S. Census to determine the population size of a particular county. There are nine classes of counties in Pennsylvania. Currently, Philadelphia is the only county to be classified as First Class and Allegheny is the only county to be classified as Second Class. The remaining Pennsylvania counties fit into the other seven classes, from Second Class A through Eighth Class. (16 P.S. 210)
Determining which class a particular county falls into can be challenging, but the County Commissioners Association of Pennsylvania (CCAP) has made navigating the class categories easier by posting a list of the First through Eighth Classes on its website: http://www.pacounties.org/PAsCounties/Pages/Counties-by-Class.aspx. This list provides the population requirements for each class, the counties that currently fall into each class, and links to the official websites of those counties.
A similar list (without the links) is also available from the Pa Courts' website: http://www.pacourts.us/news-and-statistics/research-and-statistics/dashboard-table-of-contents/resources/WebHelp/General_Information/County_Class.htm.
Want more information on the class structure and related Pennsylvania statutes? Check out Bisel's Pennsylvania Municipal Lawsource.
**Additional statute sections may also be pertinent to county class distinctions. Use the index or conduct a search in Purdon's Pennsylvania Statutes to find additional references. For a list of how to access the Pennsylvania statutes, see the Statutes tab of the Pennsylvania Legal Research guide.