Keystone is an unincorporated community and a census-designated place (CDP) located in and governed by Summit County, Colorado, United States. The CDP is a part of the Breckenridge, CO Micropolitan Statistical Area. The population of the Keystone CDP was 1,369 at the United States Census 2020.[3] The Dillon post office (Zip Code 80435) serves Keystone postal addresses.[4] The Keystone CDP includes the Keystone Resort and Keystone village.