Jefferson County, Pennsylvania
Jefferson County is a county located in the U.S. state of Pennsylvania. As of the 2010 census, the population was 45,200. Its county seat is Brookville. The county was established on March 26, 1804, from part of Lycoming County and later organized in 1830. It is named for President Thomas Jefferson. It is home to Punxsutawney Phil, the most famous groundhog that predicts when spring will come every February 2 (Groundhog Day). Geography. According to the U.S. Census Bureau, the county has a total area of , of which is land and (0.7%) is water. It has a  warm-summer humid continental climate ("Dfb") and average monthly temperatures in Brookville range from 24.8 °F in January to 68.8 °F in July, while in Punxsutawney they range from 25.7 °F in January to 69.6 °F in July. Streams. There are many named streams flowing through Jefferson County, far too many to list here. An exhaustive list is presented in a separate article. All those streams eventually flow to the Allegheny River except for Bear Run, , in the southeast which flows into the Susquehanna River. The principal streams and the area of their watersheds that lie  within the county are: Demographics. As of the census of 2000, there were 45,932 people, 18,375 households, and 12,862 families residing in the county. The population density was 70 people per square mile (27/km). There were 22,104 housing units at an average density of 34 per square mile (13/km). The racial makeup of the county was 98.97% White, 0.13% Black or African American, 0.16% Native American, 0.21% Asian, 0.01% Pacific Islander, 0.07% from other races, and 0.45% from two or more races. 0.41% of the population were Hispanic or Latino of any race. 31.1% were of German, 13.4 % Italian, 10.8% American, 9.2% Irish and 7.8% English ancestry. There were 18,375 households, out of which 30.30% had children under the age of 18 living with them, 56.80% were married couples living together, 9.10% had a female householder with no husband present, and 30.00% were non-families. 26.60% of all households were made up of individuals, and 13.80% had someone living alone who was 65 years of age or older. The average household size was 2.45 and the average family size was 2.96. In the county, the population was spread out, with 23.60% under the age of 18, 7.70% from  18 to 24, 27.20% from 25 to 44, 23.60% from 45 to 64, and 17.90% who were 65 years of age or older. The median age was 40 years. For every 100 females there were 95.70 males. For every 100 females age 18 and over, there were 92.60 males. Law and government. Jefferson County is a very safe county for the Republican Party, which has won the vote of all but two presidential elections. Voter Registration. As of February 21, 2022, there are 27,832 registered voters in Jefferson County. Recreation. Two Pennsylvania state parks are in the county. The Jefferson  County Fair is held annually in July. Communities. Under Pennsylvania law, there are four types of incorporated municipalities: cities, boroughs, townships, and, in at most two cases, towns. The following boroughs and townships are located in Jefferson County: Population ranking. The population ranking of the following table is based on the 2010 census of Jefferson County. † "county seat"