Thornton is a home rule municipality located in Adams and Weld counties, Colorado, United States.

Thornton is 10 miles (16 km) north of the Colorado State Capitol in Denver and is a part of the Denver–Aurora–Lakewood, CO Metropolitan Statistical Area.

Thornton consisted solely of farmland until 1953, when Sam Hoffman purchased a lot off Washington Street about seven miles (11 km) north of Denver.

The town he laid out was the first fully planned community in Adams County, and the first to offer full municipal services from a single tax levy, including recreation services and free trash pickup.

There were 43,230 housing units at an average density of 1,240.8 per square mile (479.1/km2).

20.1% of all households were made up of individuals, and 4.2% had someone living alone who was 65 years of age or older.

Commuter rail service to the city began on September 21, 2020, on the N Line.

Larkridge is home to national anchor tenants, big box retailers and restaurants, and has a pedestrian village.