Colo. Rev. Stat. § 31-10-904
In municipalities using paper ballots, the clerk shall cause to be printed and distributed to the election judges in the respective precincts a sufficient number of ballots. The ballots shall be sent in one or more sealed packages for each precinct with marks on the outside of each clearly stating the precinct and polling place for which it is intended, together with the number of ballots enclosed. Such packages shall be delivered to one of the judges of election of such precinct between the close of business on the Friday preceding election day or during any earlier day in which a judges' school of instruction is held, and 8 p.m. on the Monday before election day. A receipt for the ballots thus delivered shall be given by the election judge who receives them. The receipt shall be filed with the clerk, who shall also keep a record of the time when and the manner in which each of said packages was sent and delivered. The election judge receiving such package shall produce the same, with the seal unbroken, in the proper polling place at the opening of the polls on election day and, in the presence of all election judges for the precinct, shall open the package.
C.R.S. § 31-10-904
This section is similar to former § 31-10-510 as it existed prior to 1975.