This is a Real Photo postcard developed onto Azo brand photographic paper that was made between 1926 and sometime in the 1940s. The number 56 and initials "W.M.S." scratched into the developing photograph surface may refer to a publisher and/or photographer. The copyright might also be held by "W.M.S.," which seems more likely than that it belongs to what follows the symbol, the name of the city and state in which the high school existed. The approximate date is the 1920s.