In later years, Cooper would say that he had a mental hangup during major tournaments and couldn't picture himself in the winner's circle. His greatest successes were in Canada, as he won the Canadian Open in 1932 and 1937. He won 30 PGA Tour titles in all and the inaugural Vardon Trophy in 1937; his 30 titles were a record for PGA Tour players born outside the U.S. until surpassed by Vijay Singh in 2008. He was active as a senior golfer, placing sixth in the 1955 Senior PGA Championship. He was inducted into the World Golf Hall of Fame in 1992.