From wikipedia, "A township in the U.S. state of Pennsylvania is a unit of local government (see civil township) subordinate to a county, and distinct from cities and boroughs. Townships were established based on convenient geographical boundaries and vary in size from six to forty square miles (15-104 km²). There are two classifications of townships, first class and second class. To become a first class township, townships of the second class must have a population density of 300 inhabitants per square mile (120 /km2) and voters must approve the change of classification in a referendum. However, many townships have chosen to remain second class townships even though they meet the population density requirements to become first class townships."