Addendum: 10/3 (5:02 p.m.). Further research indicates that the cap could be as early as from the mid to late 1940s, but it is probably later than the 1930s. . 

Addendum: 10/2 (3:14 p.m.).  Please note that in our initial title and description the cap was mistakenly dated to the 1930s. Instead, the cap dates from the early 1950s. The title and description have been amended accordingly. 

A mid-to-late 1940s/early 1950s era San Francisco Seals professional model baseball cap. The nearly 75-year-old cap is navy with a white "SF" logo embroidered in white on the front. The cap shows a fair amount of wear along the inside band. The interior tag shows that the hat was made by Wilson. The Seals were an active minor league baseball team in San Francisco from 1903 until they moved to Phoenix in 1957. Bay Area native Joe DiMaggio played for the team from in the early 1930s as did his brothers Vince and Dom. Other prominent Seals alumni include Earl Averill, Ferris Fain, Lefty Gomez, and Paul Waner.