“The baseball public has been very kind to me. But I could not get my price here, and, as I could not go to any club playing under the national agreement, I must go into a ‘bush’ league.” Ted Breitenstein, quoted in St. Louis Globe-Democrat, January 13, 1896, p9
“The Southern Illinois league consists of Belleville, Cairo, East St. Louis, Springfield, Edwardsville, Chester and Sportsman’s Park, St. Louis. It is a ‘bush’ league, outside the pale of the national agreement.” The Rockford Daily Register-Gazette, January 15, 1896, p7
Previous earliest use (Dickson Baseball Dictionary, 3rd edition, 2009):
1ST USE. 1902. “Sioux City will belong to the north tri-state league, composed of Rock Rapids, Sheldon, Le Mars, Iowa, Flandreau, Yankton and Sioux Falls, S.D., generally known as the ‘bush leagues’” (Lincoln [Neb.] Evening News, Feb. 21; Bill Mullins).
