Wyo. Stat. Ann. § 29-6-208

Filing officers with whom notices of federal tax liens, certificates and notices affecting those liens have been filed on or before July 1, 1988, shall, after that date, continue to maintain in a file, on microfilm or by other photographic means, copies of all federal tax lien notices filed prior to July 1, 1988, notices and certificates filed in numerical order of receipt. If a notice of lien was filed on or before July 1, 1988, any certificate or notice affecting the lien shall be filed in the same office.