Complex sentence: The 1915 U.S. Open was the 21st U.S. Open, held June 17--18 at Baltusrol Golf Club in Springfield, New Jersey.
Split into simpler sentences: The 1915 U.S. Open was the 21st U.S. Open. The golf tournament was held June 17--18,1915, at Baltusrol Golf Club in Springfield, New Jersey.