To me, Reconstruction ended because the North got tired of holding the South down and doing so for the sake of black people.
The people of the North were not all that comfortable with the idea of running the South by military government. That really goes against all American values. As the South got more and more upset about the military rule, the North came under more pressure to end it.
If there had been some "good" reason for the military rule, people in the North might have supported it. But, by 1876, the only reason for military rule was to protect black rights. Most in the North did not care at all about black rights.
So the North got tired of "oppressing" the South since that was only being done for the sake of the freed slaves.
Civil War Reconstruction is one of those rare instances in U.S, History by which one can neatly place an "era" of time neatly into an exact beginning and ending date. This is due to the fact that Reconstruction begins when the war ended at the surrender at Appomattox in 1865 and it officially ended upon the ratification of the U.S. Congressional compromise in 1877.
Essentially the compromise is the solution to the "controversial" presidential election of 1876. In this election neither the Democratic nominee James Tilden or the incumbent Republican nominee Rutherford B. Hayes were able to win because no one had earned more than half of the electoral necessary to carry victory. The U.S. Constitution grants power to the U.S. House of Representatives to solve such issues but it does provide specifics; it essentially empowers the House to create such parameters to choose the President if the electoral college to do so. Due to the continued contentiousness between northern and southern states since the Civil War the Democrats, for the most part, represented the interests of the South and the Republicans that of the North. In an effort to allow "fairness" the U.S. House created a committee of fifteen to solve the outcome of this presidential election.
The Committee of Fifteen, as they have since been known as, was made up of seven Democrats, seven Republicans and a member of the Supreme Court (who happened to be appointed by a Republican President). The results of the work of this committee was the Compromise of 1877. The compromise, in brevity, made the Republican Rutherford B. Hayes the president and in return the Democrats got Military Reconstruction to end along with the removal of all troops that had been enforcing national law since the conclusion of the Civil War in occupational manner in the former Confederacy. This compromise ultimately ended Civil Reconstruction as we know it.
While parts of Reconstruction (The Freedmen's Bureau, land reform, etc.) had already stopped or had never taken place by 1877, the real reason why Reconstruction ended was that the Union Army left the South, and therefore, no authority was left to enforce Reconstruction's elements, and southern states were left to their own devices.
The army had shrunk radically by that time from its Civil War levels, and it was expensive to maintain an occupation of the South. Also, it was politically convenient. The stalemate of the Election of 1876, in which the Republicans and Rutherford B. Hayes had cheated in order to win, necessitated a compromise between the political parties. The most important condition of the Compromise of 1877 was the removal of Union troops. This was the practical end of Reconstruction.
The end of the Reconstruction era was between the years of 1873 to 1877. There were a few key events that ended the Reconstruction era, and one of these was the switch from Republican control to Democratic control of the House.
A depression within the economy was raging throughout the country in 1873. Because focus turned elsewhere, northern voters became less interested in the Reconstruction of the south and more focused on the economy in the north. Unemployment was rising and jobs became scarce forcing many white to turn and focus on their own financial situation instead of the financial situation of the South. The Democrats turned their focus to the financial situation instead of punishing the KKK and securing right for freed slaves.
Republicans, after a decade of trying to rebuild the South, grew tired of putting all of their effort in to fixing the south and all of their problems. The Supreme Court continually struck down radical Republicans efforts to rebuild certain parts of the South as the Democrats took control of the government. The Compromise of 1877 was the final act of the end of the Reconstruction era. This compromise removed all federal troops from the South