Luzerne County is a county in the Commonwealth of Pennsylvania. According to the United States Census Bureau, the county has a total area of 906 square miles, of which 890 square miles is land and 16 square miles is water. It is Northeastern Pennsylvania's second-largest county by total area. As of the 2020 census, the population was 325,594, making it the most populous county in the northeastern part of the state. The county seat and largest city is Wilkes-Barre.