McCormick's opposition to President Grant's Indian "Peace Plan" allowed him to win re-election to his third term without opposition. The term also saw him win a number of reforms. Using an argument that qualified individuals were not applying to be territorial officials because the cost of living exceeded the pay for various positions, he was able to have the pay for territorial legislators raised to US$6 per day and territorial governor's pay raised to US$3,000 per year. He also succeeded in having the administration of U.S. territories moved from the State Department to the Department of the Interior, with the transfer occurring on March 1, 1873. McCormick also worked on a bill to restrict the killing of American Bison except for use as food, legislation resolving citizenship issues of Mexican-born residents of Arizona who lived in land acquired through the Gadsden Purchase, further expansion of mail routes and criminalization of acts that damaged or destroyed parts of the new military telegraph system. McCormick chose not to run for a fourth term.