The City of Thornton is a Home Rule Municipality in Adams and Weld counties in the U.S. state of Colorado, located in the northeast quadrant of the Denver-Aurora-Broomfield, CO Metropolitan Statistical Area. Thornton is 10 miles (16 km) north/northeast of downtown Denver. The United States Census Bureau reported the city's growing population at 118,772 on April 1, 2010, a 44.2% increase from the 2000 Census population of 82,384.