[16][17] Still little-known outside his native Missouri, Simpson faced a strong field that included Fred W. Kelly, the 1912 Olympic champion and world record holder at 15.0.

[25][26][note 1] He then broke the record in a dual meet against Iowa State on May 6, running 14.8; he also won the low hurdles, the 100 yd dash and the long jump.

[31][32][33] His hurdles rivals were also in strong form, however;[34] Kelly and Murray both ran 15.0 that spring,[31] and on May 13 Earl Thomson, a Canadian-American, defeated them both in a Stanford race and tied Simpson's fresh record of 14.8.

[3][31][32] Sporting Life's Daniel Ferris named Simpson and Ted Meredith, who had broken the world records for both 440 yards and 880 yards, the leading American track and field athletes of 1916,[34] while Lou Handley singled Simpson out in his Pittsburg Press recap of the year.

[48] He led the Tigers to another Missouri Valley Conference title, winning the long jump and both hurdles races.

[49] He also won all three events at the Western Conference meet;[50] his winning time in the 220 yd low hurdles was 24.2, a world best for that distance around a curve.

[54] After the 1917 season Simpson joined the United States Army and attended the officers' training camp at Fort Sheridan; he became a lieutenant and track and field instructor for the 91st Division.

[60] On September 7, 1919, Simpson won the 120 yd hurdles at the Knights of Columbus Olympics, an Armed Forces meeting held at Camp Dix, defeating former national champion Harold Barron;[61] Simpson's time of 15.0 was the fastest in the world that year.

[74][75] In 1939 Simpson became a coach and athletic director in Hungary,[76] where he stayed for the next years despite World War II.

[79] After the war he served as the Army's track and field director in Europe;[79] he was recalled up to the United States in 1948 to coach Army and Air Force Olympic hopefuls at the Lackland Air Force Base in San Antonio.

[83] Simpson married Meryl Leavell, women's tennis champion at the University of Missouri, in May 1918 after a short engagement.