In February 1934 Bonthron defeated 1932 and 1933NCAA champion Glenn Cunningham in an indoor meet in New York by several inches.[7] On June 16 Bonthron was again on the losing end of a mile world record, as Cunningham beat him in the Princeton Invitational Mile in 4:06.7.[8] However, Bonthron came back to beat Cunningham at the NCAA championships on June 23 in a meet record time of 4:08.9.[9] A week later at the national championships in Milwaukee, Bonthron defeated Cunningham again. The race was over 1500 meters; Cunningham went out hard and was still well ahead a hundred yards from the tape, but Bonthron came through with a blistering sprint to win by two feet in a new world record time of 3:48.8.[6][10][11] Cunningham's time was 3:48.9, also inside Luigi Beccali's previous record of 3:49.0.[6][11] Bonthron won the 1934 Sullivan Award as the top amateur athlete in the United States.[1][12]
Although Bonthron originally intended to retire from running after graduating,[13] he ended up not doing so; he, Cunningham and Gene Venzke remained America's leading milers in 1935.[14] However, Bonthron was not in his best shape in 1936 and only placed fourth at the Olympic Trials (behind Cunningham, Archie San Romani and Venzke),[15] failing to make the Olympic team and subsequently retiring.[16]
In April, 1936, Bonthron, along with many other sports champions and stand outs, was honored at a banquet in Detroit, MI.[17] This Banquet was the first celebration of Champions Day.