Answer:
The presidential election of 1876 angered Democrats because they thought the voting system was unfair.
Step-by-step explanation:
The presidential election of 1876 resulted in the election of the Republican Rutherford B. Hayes against the Democrat Samuel Jones Tilden, who had nevertheless obtained the absolute majority of the popular votes.
This election was acquired only after a very important litigation, which almost led to a constitutional impasse. The acceptance by the Democrats of the election of Hayes was undoubtedly a political trade by which the Republicans put an end to the Reconstruction, and thus to the trusteeship of the Southern States.
In any case, the Southern Democrats, called Dixiecrats, were able, after 1877, to regain power in all the former Confederate States and reintroduce a policy of racial discrimination through the Jim Crow Laws. At the same time, Republicans were disappearing from the political landscape of the southern states before reappearing only in the 1960s and 1970s.