Lawrence County is the easternmost county in the U.S. state of Illinois. At the 2020 census, the population was 15,280. Its county seat is Lawrenceville.

Lawrenceville is a city in and the county seat of Lawrence County, Illinois, United States, located along the Embarras River. The population was 4,348 at the 2010 census. Lawrenceville is located in southeast Illinois, northwest of Vincennes, Indiana.