Bleacher (1887)

“Hoover thought it time to give Wilkes-Barre a chance to cheer, so he drove the ball through Crane’s legs, stole second and third base in a manner peculiarly Hooverian, and scored while ‘Kid’ Williams was trying to pick up the ball that had bounded out of his hands to one side. Excellent base running that brought down she [sic] house—the ‘bleachers’ rather.” Scranton Republican, September 2, 1887, p4 [Richard Hershberger]

Previous earliest use (Dickson Baseball Dictionary, 3rd edition, 2009):
1ST USE. 1889. “Tobogganed agin,’ sententiously replied a mournful looking bleacher” (The World [New York]