Thornton is a city in Calhoun County, Arkansas, United States. The population was 407 as of the 2010 census, down from 517 in 2000. I…Thornton is a city in Calhoun County, Arkansas, United States. The population was 407 as of the 2010 census, down from 517 in 2000. It is part of the Camden, Arkansas micropolitan area. Thornton is located in northern Calhoun County. U.S. Route 79 passes through the city, leading northeast 6 miles to Fordyce and southwest 26 miles to Camden. U.S. Route 167 cuts across the southeast corner of the city limits, leading north to US 79 and Fordyce and south 16 miles to Hampton, the Calhoun County seat.