I usually consider the 13th 14th and 15th amendments the answer to that question. That would make it 1870 or so. The 13th was ratified in 1865 (Dec.) and the 15th in 1870.
I included the 14, but you have to be a lawyer to see the implications of the 15th. Of all the amendments, in beginning civics courses none take up more room in their commentary than the 14th. Read the wording of Section 2. That allowed voting.
The point is none of these amendments had much in the way of teeth. It was not until 1964 with the passage of the Civil Rights Act that full universal rights were given to each citizen of the United States. Poll taxes and Literacy tests were eliminated. Their practice was made illegal.
If you were African American, you would not think reconstruction had ended until Johnson signed the Civil Rights Act and The Voting Rights act into Law (the latter in 1965).
