"It was officially adopted as a United States military bolt-action rifle on June 21, 1905, and saw service in World War I. It was officially replaced as the standard infantry rifle by the faster-firing, semi-automatic 8 round M1 Garand, starting in 1937. However, the M1903 Springfield remained in service as a standard issue infantry rifle during World War II, since the U.S. entered the war without sufficient M1 rifles to arm all troops"
Thanks Wikipedia, that was easy!