I spent two years working as a claims rep for Social Security.
One guy who applied for retirement was a Black guy. He did not have a birth certificate so I had to check other records. One was the original form he filled out when he applied for a SSN.
One of the common records was early school records. He had gone to grammar school in Mississippi in the early 1900s. I sent off a request for his school records not really expecting much.
To my surprise they had really accurate and detailed records. This from an all Black school district in the middle of nowhere in Mississippi.
The black literacy rate 120 years ago was higher than it is today!