Kilgore is a city in Gregg and Rusk counties in Texas, United States. Located where Interstate 20 and US 259 converge just south of the Sabine River. Over three-fourths of the area within city limits are located in Gregg County, the remainder in Rusk County. The population was 12,975 at the 2010 census and 13,376 at the 2020 census.