Wyo. Stat. Ann. § 15-5-301

The governing body of any city or town maintaining a paid police department and having a population of more than four thousand (4,000), after ten (10) days published notice and a public hearing thereon, may establish a policemen pension fund. Any such fund established prior to July 1, 1981 shall be divided into two (2) separate accounts to be known as the existing account and the new account. The existing account shall consist of contributions from police officers employed prior to July 1, 1981 and city or town contributions made in those officers' behalf. The new account shall consist of contributions made from police officers employed after June 30, 1981 and city or town contributions made in those officers' behalf.