Harper started his career in 1916 with the Detroit Tigers and stayed there through the 1918 season. After not playing in 1919, he spent the 1920 and 1921 seasons in the minors. Then he played for the Cincinnati Reds from 1922-1924 before he headed over to the Philadelphia Phillies in a three way trade where he stayed through the 1926 season. He was then sent to the Cardinals for the 1927 season where he played in the World Series against the Yankees. After his trade for O'Farrell in 1928, he played in the 1928 World Series against the Yankees, then sold to the Boston Braves for the 1929 season; he came there in the same transaction that saw future Hall of Famer Rabbit Maranville go to the Braves as well. That would be his Harper's last season in the big leagues.
When Harper came up with the Tigers, he played in right field along side Ty Cobb and temporarily took over right field when HOF Sam Crawford was finished playing. During the 1916 season, 21 year old Harry Heilmann took over the right field for the Tigers. Harper played the brief time between the two future HOFs in what was a tremendous era for the franchise. Not only was Cobb with them through the 1926 season, either Crawford and Heilmann manned RF from 1907 to 1929. After Harper's trade from New York to St Louis, an 18 year old OF named Mel Ott started playing RF for the Giants. His Hall of Fame career started at that moment in 1928 and it would last through 1945.
George Harper was traded 4 different times and purchased one other time. In fact, there is no known transaction that showed how Harper went from Detroit to Cincinnati. He would later manage the El Dorado Lions of the East Dixie League in 1934 and 1935. He did, however, stick around in the minor leagues for the better part of the 1930s. Harper hit .303 for his career over his 11 seasons, having 1030 hits in that time. He would pass away on August 18, 1978 at age 86.