The oldest currently-running independent league, the Frontier League was formed in 1993. Following the 2020 season the league was named one of MLB’s Partner Leagues.
Bill Lee (Commissioner) 1993 – 2020
1990s
The dates of two of these balls are imprecise, but it’s believed the first one is from the early 1990s, while the third is from the late 1990s. The third ball (with the league stamp but without the logo) is dated precisely to 1996.