Wyo. Stat. § 24-1-129: Marking of bypasses.

It is declared to be the policy of the state of Wyoming that where the Wyoming department of transportation has by law authorized a bypass to be built around any incorporated city or town, or an unincorporated community of the state of Wyoming, regardless of the population of such city, town or unincorporated community, the officially designated state highway and federal highway markings shall remain on the existing highway through the incorporated city or town or unincorporated community and the existing highway shall be retained and the new bypass highway shall carry the designation "bypass" or other similar markings.