“Flanagan’s round-tripper nets three runs.” Rochester Democrat and Chronicle, July 25, 1907, p17
Previous earliest use (Dickson Baseball Dictionary, 3rd edition, 2009):
1ST USE. 1939. “[Bill] Dickey cracked his round-tripper over Rip Radcliff’s reaching glove” (The New York Times, Sept. 22; David Shulman).
