Final answer:
The official end of Reconstruction in 1877 was marked by the Compromise of 1877, which led to the withdrawal of federal troops from the South.
Step-by-step explanation:
The official end of Reconstruction in the United States occurred in 1877 with the Compromise of 1877. This political agreement between Republicans and Democrats effectively ended Reconstruction and signaled the withdrawal of federal troops from the South. The compromise resulted in Rutherford B. Hayes becoming president and brought an end to the remaining federal efforts to protect the rights of newly freed African Americans in the South.