Newton is a city in and the county seat of Harvey County, Kansas, United States. As of the 2020 census, the population of the city was 18,602. Newton is located 25 miles (40 km) north of Wichita at the intersection of Interstate 135, U.S. Route 50, and U.S. Route 81 highways. The city of North Newton is located on the north side of Newton and exists as a separate entity.