Final answer:
Voter suppression tactics, economic factors, and social discrimination caused the decrease in black legislators and political participation at the end of Reconstruction.
Step-by-step explanation:
The decrease in black legislators and political participation at the end of Reconstruction was caused by voter suppression tactics, economic factors, and social discrimination. White Southern Democrats used violence, voting law reforms, and other methods to marginalize black voters and prevent them from participating in politics.
Economic factors, such as the reliance on cotton and the depressed prices of the crop, further impoverished the region and discouraged investment and innovation.