[2] In 1940, Johnson initially played for the minor league Atlanta Black Crackers, then quickly moved up to the Toledo-Indianapolis Crawfords before ending up on the Kansas City Monarchs, all at the age of 17.

[2] Afterwards, Johnson played a key role in the 1941 and 1942 Negro League World Series titles won by the Monarchs, a team that included future Hall of Famers Satchel Paige and Hilton Smith.

[2] Following his discharge in 1946, Johnson returned to the Monarchs and went 9-3 with a 3.46 earned run average,[3] helping his team win another pennant, even though he did not pitch in the Series.

[2] In 1951, Johnson played for the St. Hyacinthe Saints club based in the Canadian Provincial League, where he posted a 15-14 record with a 3.24 ERA and a league-high 172 strikeouts.

[4] During the midseason, Johnson was traded by Chicago along with Mike Fornieles, George Kell and Bob Nieman to the Baltimore Orioles in exchange for Jim Wilson and Dave Philley.

[3] In between, Johnson played winter ball with the Spur Cola Colonites club of the Panamanian League, who won the 1950-51 pennant and represented Panama in the 1951 Caribbean Series.