He began his pro career with the Portsmouth Spartans in 1931 for a salary of $75 per game. In 1934 joined the Detroit Lions. With Emerson blocking and leading the way the 1936 Lions team set a rushing record of 2,885 yards in a twelve-game season that lasted 36 years. It was finally broken by the Miami Dolphins in 1972 in a fourteen-game season. Emerson retired in 1937 to become line coach under Potsy Clark for the Brooklyn Dodgers, but then briefly returned as player.