Wyo. Stat. § 31-5-402 (2026)

(a) The driver of any vehicle shall obey the instructions
of any official traffic-control device applicable thereto placed
or held in accordance with this act unless otherwise directed by
a police officer, subject to the exceptions granted the driver
of an authorized emergency vehicle in this act.

     (b) No provision of this act for which official
traffic-control devices are required shall be enforced against
an alleged violator if at the time and place of the alleged
violation an official device is not in proper position and
sufficiently legible to be seen by an ordinarily observant
person. Whenever a particular section does not state that signs
are required, the section is effective even though no signs are
erected or in place.

     (c) Whenever official traffic-control devices are placed
or held in position approximately conforming to the requirements
of this act, the devices are presumed to have been so placed or
held by the official act or direction of lawful authority unless
the contrary is established by competent evidence.

     (d) Any official traffic-control device placed or held
pursuant to the provisions of this act and purporting to conform
to the lawful requirements pertaining to the devices is presumed
to comply with the requirements of this act unless the contrary
is established by competent evidence.