Colorado Revised Statutes Title 1. Elections § 1-5-401. Method of voting

(1) For all general, primary, congressional vacancy, coordinated, odd-year, and recall elections, and for any election in which the governing body of a political subdivision other than a county determines that an election shall be by mail ballot, the county clerk and recorder or designated election official for the political subdivision, as applicable, shall conduct the election by mail ballot;  except that votes cast at voter service and polling centers may be by paper ballots or by electronic or electromechanical voting systems.

(2) For any election that the governing body of a political subdivision determines will be an independent mail ballot election, the designated election official for that political subdivision shall conduct the election by mail ballot in accordance with article 13.5 of this title.