Mangham was a two-time All-State Selection and New Castle Highschool, graduating in 1956. Asides from basketball, Mangham also set a state record in the High Jump with a jump of 6'9 3/4“. This jump raised the record 4 3/4” and stood for 18 years.

Mangham was drafted by the New York Knicks in the 10th round of the 1960 NBA Draft. He later switched to the now defunct American Basketball League, playing for the Pittsburgh Rens, where he finished 23rd on the All-Time scoring list with 1067 points.

After retiring from professional basketball Mangham worked as a Sales Representitive for Frank Fuhrer Wholesale, a Coors Beer distributer until he retired in December 2004.