He is remembered for his short career as leader of anti-Tammany Hall reform politics in New York, as well as for his early death as an Army Air Service officer during a training flight in Louisiana amid World War I.

"[3] Former President Theodore Roosevelt, endorsing Mitchel's re-election bid in 1917, stated that he had "given us as nearly an ideal administration of the New York City government as I have seen in my lifetime.

Mitchel began his career as assistant corporation counsel and then became a member of the Commissioners of Accounts, from which he investigated city departments.

Mitchel, with the help of Henry Bruere and other staff members of the Bureau of Municipal Research turned the insignificant Commissioners of Accounts into an administration of importance.

[7] As the 1913 mayoral election approached, the Citizens Municipal Committee of 107 set out to find a candidate that would give New York "a non-partisan, efficient and progressive government."

The bullet ricocheted off a pedestrian and hit Frank Lyon Polk, New York City's corporation counsel, in the chin.

Mitchel was heavily criticized for combining vocational and academic courses in the Gary Plan, and began to trim the size of the Board of Education and attempted to control teachers' salaries.

His reelection campaign suffered, as many New Yorkers felt he cared more about American involvement in World War I, socializing with the city's elite, and fiscal management than local issues.

[7] He narrowly lost the Republican primary to William M. Bennett after a contentious recount, but then ran for re-election as a pro-war Fusion candidate.

[11] After losing re-election, Mitchel joined the Army Air Service as a flying cadet, completing training in San Diego and obtaining the rank of major.

[14] A bronze memorial plaque with Mitchel's likeness is affixed between the two stone pylons at the western end of Hamilton Hall at Columbia University.

A plaque of his likeness is located on an entrance to the base of the Jacqueline Kennedy Onassis Reservoir jogging track in Central Park.