Keystone is a home rule town located in Summit County, Colorado, United States. The town is a part of the Breckenridge, CO Micropolitan Statistical Area. The population of the Keystone census-designated place was 1,369 at the United States Census 2020. The Dillon post office serves Keystone postal addresses. The municipality includes the Keystone Resort and Keystone village. Keystone residents voted to incorporate on March 28, 2023, becoming a municipality on February 8, 2024.