A county or school district is rural when the number of people per square mile within the county or school district is fewer than 291. Counties and school districts that have 291 people or more per square mile are considered urban.

The U.S. Census Bureau has not yet identified 2020 urbanized areas. Therefore, the Center is continuing to use the 2010 municipal definition of rural as follows: a municipality is rural when the population density within the municipality is fewer than the 2010 statewide average density of 284 people per square mile, or the total population is less than 2,500, unless more than 50 percent of the population lives in an urbanized area as defined by the U.S. Census Bureau. All other municipalities are considered urban.

According to the Center's definition, there are 48 rural counties and 19 urban counties in Pennsylvania. In 2020, nearly 3.4 million residents called these rural counties home, or 26 percent of the state's 13.0 million residents.
At the school district level, 238 of the state's 500 public school districts are rural. During the 2020-2021 school year, 374,732 public school students attended school in rural districts, or 25 percent of the state's nearly 1.41 million public school students.
At the municipal level, 1,592, or 62 percent, of the state's 2,562 municipalities are rural and 970 municipalities, or 38 percent, are urban.