St. Petersburg Saints
The St. Petersburg Saints of St. Petersburg, Florida predate their league. The Saints began as an independent club in 1914, playing at Coffee Pot Park by Coffee Pot Bayou, the modest ballfield where spring training in Florida was effectively born: Mayor Al Lang lured the St. Louis Browns there in 1914, and the Philadelphia Phillies followed from 1915 to 1918, launching St. Petersburg's century-long run as a spring training capital.
The Saints joined central Florida's professional league as an expansion club in 1920 and won the championship in 1922. They shared in one more title in 1928, the league's tumultuous final season before it went dark for the Depression. When the Saints name returned after the war, the club joined the Florida International League from 1947 to 1954, winning the 1951 championship, then came back to its original circuit in 1955 and won back-to-back titles in 1958 and 1959 as a New York Yankees affiliate.
The Saints name retired after 1965, when a new affiliation renamed the club, but the franchise line it started ran in St. Petersburg for decades more. Few teams anywhere can claim their ballpark hosted the birth of an American institution; the Saints can.
The Saints' league began play in 1919 as a Class D circuit of six teams clustered across central Florida, tracing what would later become the I-4 corridor decades before the interstate existed. The circuit ran through 1928, went dark during the Depression, returned in 1936, paused again for World War II, and resumed in 1946. Unlike most minor leagues of the era, it never truly died; the same circuit still operates across Florida today.