The league has produced 38 players who have gone on to play professionally in the top leagues. This independent professional baseball league began in 2006 and has six clubs across the Midwest, including Sioux City, Illinois, Indiana, Wisconsin, Kansas, Nebraska, North and South Dakota, Texas, and Winnipeg, Manitoba, Canada. The Chicago White Sox are the most successful franchise with five championships; the Kansas City Royals, Minnesota Twins, Oakland Athletics, and Tampa Bay Rays each have one. In 1871, the first official game was played between the Chicago Unions and the Chicago Red Stockings, with the Red Stockings winning 2-1. In 1902, the Chicago Cubs became the first modern major league team when they started playing games against other teams instead of just each other. However, it wasn't until after the 1917 season that the United States entered World War I, so baseball was not considered "essential industry" by then-newly formed Federal Bureau of Investigation (FBI) agents who conducted security interviews with players before they would be allowed to return to work. Thus, no federal government officials interviewed during this period of time have ever admitted to seeing any evidence of gambling activity. After the war, a number of players were accused of using their positions on baseball teams to gain access to military information; however, none of these allegations could be proven and all charges were dropped.