Hartsel is a census-designated place (CDP) in and governed by Park County, Colorado United States.

Founded in 1880, Hartsel is close to the geographic center of the state, and is often referred to as "The Heart of Colorado".

The namesake of the community is Samuel Hartsel,[5] a local farmer and cattle rancher who came to Park County in 1860 and left in 1908.

He developed the Hartsel hot springs and built a sawmill, blacksmith shop, and a trading post to lay the groundwork for the town.

According to the United States Department of Agriculture, the Plant Hardiness zone is 3b with an average annual extreme minimum temperature of −30.7 °F (−34.8 °C).