The interpretation of post-Civil War Reconstruction in the United States that Dunning and his students propounded was the dominant theory taught in American schools for the first half of the 20th century. The viewpoint of Dunning and his followers favored the reversal of political gains the freed people had made in the area of civil rights during the period of Reconstruction.

Dunning and his followers also criticized white Southerners who did not stand with the Confederacy during the Civil War and who joined the Republican Party after the war. Former Confederate leaders referred to the largest group of white Southern Republicans who did not identify with the goals of former plantation owners as Scalawags. They also referred to Northern whites who moved to the southern part of the United States after the war as Carpetbaggers. Both were derisive terms that Dunning and his followers popularized.

Reconstruction's caricatures include the "carpetbaggers", whom southern whites portrayed as greedy interlopers exploiting the South; the "scalawags", who were traitorous southern whites collaborating with the Yankees; the freedmen, whom the Dunning School portrayed as sometimes violent and depraved and at other times ignorant and lost; "copperheads" who were Northerners who promoted peace and opposed war measures taken by President Abraham Lincoln and who were given that moniker by their Republican opponents; and former Confederates, who were the heroes of the story told by the Dunning School of historians. Dunning and his followers portrayed former plantation owners as honorable people with the South's best interests in mind, according to a historical essay on myths of Reconstruction.[McCrary, Peyton, "The Reconstruction Myth" in Encyclopedia of Southern Culture]

Interpreting the impeachment of President Andrew Johnson Dunning lent academic respectability to the late 19th century's view of Reconstruction history pioneered by segregationist Southern Democrats and their northern sympathizers. Dunning wrote from the point of view of the defeated South and painted the Radical Republicans as villains. His interpretation served the ideological purposes of upper class southern whites eager to put the divisions of the Civil War behind. The Dunning viewpoint saturated public memory in history textbooks until the dawn of the modern civil rights era. Dunning School influence is evident in John F. Kennedy's book Profiles in Courage, which admired Edmund G. Ross, the Kansas Republican senator who cast the vote that acquitted Johnson.[Joshua Zeitz The New Republic, 18 January 1999, pp. 13-15]