That nickname would stick with the various Peoria clubs for the next couple of decades, including their first stretch with the Three-I League from 1905 to 1917.

After the resumption of following the peak of American involvement in World War I, the Peoria Tractors name gained favor in 1919, with the growth of the nearby branch of the company later called Caterpillar Inc.

In 1923, the team opened a new ballpark called Woodruff Field in honor of a long-time mayor of Peoria.

This club disbanded after 1957, and Peoria was again without professional ball, for the next 25 years until the current Chiefs set up shop.

During the new park's first year, the team set a franchise attendance record of 254,407 and won the Midwest League championship.

Baseball Hall of Famer Ryne Sandberg was hired to manage the 2007 Chiefs, which went 71–68 and finished the second half 40–30 in a tie for the division title, but missed the playoff on a tiebreaker.

The team set a Midwest League single-game attendance record on July 29, 2008, when the Chiefs drew a crowd of 32,103 to Wrigley Field in Chicago for a game against the Kane County Cougars.

The Chiefs' affiliation with the Cubs ended after the 2012 season,[4] and they entered into a player-development contract with the St. Louis Cardinals.

The teams played again the following day, and in the first inning, Chiefs pitcher Julio Castillo hit Dragons batter Zack Cozart in the head.

On August 8, 2009, Castillo was convicted of felonious assault causing serious physical injury and was sentenced to 30 days in jail.

[9] In April 2010, a judge released Castillo from probation "on the condition that he leave the United States and not return for a minimum of three years.