There are 13 municipalities in Sullivan County, Pennsylvania, in the United States. Pennsylvania law defines the two kinds of incorporated municipalities in Sullivan County: four boroughs and nine townships. This list gives their names and etymologies, dates settled and incorporated, what they were formed from, area, population, and location within the county. In the 2010 census, the population of Sullivan County was 6,428, making it an "Eighth Class County", defined by Pennsylvania law as "having a population of less than 20,000 inhabitants". Its county seat is Laporte, which was the smallest county seat in Pennsylvania by population, as of 2001.