Perry Park was to the Keokuk Westerns of the National Association during the 1875 season, so it is considered a major league ballpark by those who count the NA as a major league.
References
Perry Park (Iowa) Wikipedia(Text) CC BY-SA
Perry Park was to the Keokuk Westerns of the National Association during the 1875 season, so it is considered a major league ballpark by those who count the NA as a major league.