harrington was born in louisville, kentucky and attended the university of louisville. starting out on two wheels, harrington won a number of championships and achieved much success in the world of ama motocross and supercross. in 1986 sports car magazine picked harrington as one of the three most promising drivers in the u.s. he was a multiple race winner in toyota formula atlantic, finishing third in the 1988 championship despite running the uncompetitive ralt chassis. he was the only person ever to win a race in the 1988 ralt. from 1992 through 1994, harrington had much success in the scca can-am series. during his tenure in the series, he won more races than any other driver. he won the 1992 championship and scored race wins in every season.