Carter had outstanding high school football career at Bonita High School, where he was considered by some observers to be one of the top high school running backs of the time. He ran for 4388 yards with 70 touchdowns during his three years on the Bonita varsity team, breaking records set by Glenn Davis in the process. Carter also participated in track and field in high school, and was the California state champion in the 100-meter dash in his junior year, running the race in 9.7 seconds.
College
After high school, Carter signed to play college ball at the University of Southern California. In his freshman year, Allen led the USC freshman team in rushing. But as a sophomore in 1972, he suffered leg injuries and fell behind Anthony Davis and Rod McNeill on the varsity team at tailback. Davis became the team's star tailback for the next three years, with Carter playing behind him. Carter rushed 30 times for 226 yards, a 7.5 average, that season, as USC won the National Championship. As a junior in 1973, again playing behind Davis and McNeill, Carter rushed 43 times for 294 yards, a 6.8 yard average. As a senior in 1974, Allen played behind only Davis, and rushed for 580 yards on 111 carries, a 5.2 average, helping USC to another National Championship. Allen played a key role in USC's victory in the 1975Rose Bowl Game, rushing for 75 yards after Davis suffered a rib injury in the first half of the game.
Professional career
Carter was drafted by the Patriots in the 4th round with the 86th pick of the 1975 NFL draft. The Patriots had received the pick from the Cleveland Browns in exchange for wide receiverReggie Rucker. With the Patriots he was reunited with fellow running back Sam Cunningham, who had been his fullback on the 1972 USC team. Carter was primarily a kick returner for the 1975 Patriots. He rushed only 22 times for 95 yards, a 4.3 yard average. He also caught 2 passes for 39 yards. He had a successful season as a kickoff return man, returning 32 kicks for 879 yards and a 27.5 yards per return average. His 32 returns ranked 7th in the NFL, his 879 yards ranked 6th and his 27.5 yard average ranked 3rd. In the final game of the season against the Baltimore Colts, Carter returned the opening kickoff 99 yards for a touchdown. His 99-yard return was the 2nd longest in the NFL that season. It also set a Patriots record for longest kickoff return, which was broken by Raymond Clayborn's 100 yard return in 1977. The touchdown was also enough to tie the league lead for kickoff return touchdowns for the season. In the first game of the 1976 season, Carter saw little action due to a knee injury. He returned just one kickoff for 19 yards and did not have any rushes or receptions. He was waived by the Patriots the following week and was signed by the New York Jets. He was waived by the Jets shortly thereafter.
Post-retirement
After his football career ended, Carter became a teacher, activities director, and assistant football coach at Anaheim High School. He later became Anaheim's varsity football head coach, during which time Carter coached future NFL running back Reuben Droughns.
