Pennsylvania is divided into 67 counties. Counties are further subdivided into municipalites that are either incorporated as cities, boroughs, or townships. One county, Philadelphia County, is coterminus with the city of Philadelphia after it was consolidated in 1854.
There are a total of 56 cities in Pennsylvania, which are classified, by population, as either first, second, or third class cities. Philadelphia, Pennsylvania's largest city, has a population of 1,547,297 and is the state's only first class city.Pittsburgh (311,647) and Scranton (71,944) are second class and second class 'A' cities, respectively. The rest of the cities, like the third and fourth largest—Allentown (107,815) and Erie (103,571)—to the smallest—Parker with a population of only 738—are third class cities. First and second class cities are governed by a "strong mayor" form of mayor–council government, whereas third class cities are governed by either a "weak mayor" form of government or a council–manager government.
Boroughs are generally smaller than cities, with most Pennsylvania cities having been incorporated as a borough before being incorporated as a city. There are 958 boroughs in Pennsylvania, all of which governed by the "weak mayor" form of mayor–council government.
Townships are the third type of municipality in Pennsylvania and are classified as either first class or second class townships. There are 1,454 second class townships and 93 first class townships. Second class township can become first class townships if it has a population density greater than 300 inhabitants per square mile (120 /km2) and a referendum is passed supporting the change.
There is one exception to the types of municipalities in Pennsylvania: Bloomsburg was incorporated as a town in 1870 and is, officially, the only town in the state. In 1975, McCandless Township adopted a home-rule charter under the name of "Town of McCandless", but is, legally, still a first class township.