According to the U.S. Census Bureau, the county has a total area of, of which is land and is water. It has a humid continental climate and average monthly temperatures in Waynesburg range from 28.9 °F in January to 71.9 °F in July.
Adjacent counties
Washington County
Fayette County
Monongalia County, West Virginia
Wetzel County, West Virginia
Marshall County, West Virginia
Demographics
As of the census of 2010, there were 38,686 people, 14,724 households, and 9,970 families residing in the county. The population density was 67 people per square mile. There were 16,678 housing units at an average density of 29 per square mile. The racial makeup of the county was 94.6 percent White, 3.3 percent Black or African American, 0.2% Native American, 0.3 percent Asian, 0.0 percent Pacific Islander, 0.7 percent from other races, and 1.0% from two or more races. 1.2 percent of the population were Hispanic or Latino of any race. There were 14,724 households out of which 29.3 percent had children under the age of 18 living with them, 51.5 percent were married couples living together, 10.9 percent had a female householder with no husband present, and 32.3 percent were non-families. 27.0 percent of all households were made up of individuals and 11.7 percent had someone living alone who was 65 years of age or older. The average household size was 2.42 and the average family size was 2.91. In the county, the population was spread out with 19.9 percent under the age of 18, 9.9 percent from 18 to 24, 25.5 percent from 25 to 44, 29.3 percent from 45 to 64, and 15.3 percent who were 65 years of age or older. The median age was 41.1 years. For every 100 females there were 106.2 males. For every 100 females age 18 and over, there were 105.6 males.
Government and politics
Voter registration
As of November 7, 2017, there were 21,671 registered voters in the county. Democrats hold a majority of 3,621 voters ; there was 11,659 registered Democrats, 8,038 registered Republicans, 1,858 voters registered to other parties, 64 to the Libertarian Party and 52 voters registered to the Green Party.
Greene County's development commission has assisted area business since 1998. The Meadow Ridge office park has served the county since the early 2000s.
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 Greene County:
Boroughs
Carmichaels
Clarksville
Greensboro
Jefferson
Rices Landing
Waynesburg
Townships
Aleppo
Center
Cumberland
Dunkard
Franklin
Freeport
Gilmore
Gray
Greene
Jackson
Jefferson
Monongahela
Morgan
Morris
Perry
Richhill
Springhill
Washington
Wayne
Whiteley
Census-designated places
s are geographical areas designated by the U.S. Census Bureau for the purposes of compiling demographic data. They are not actual jurisdictions under Pennsylvania law. Other unincorporated communities, such as villages, may be listed here as well.