The following is from the State Archives and is the source of where I had seen the reference to those that had signed the "Oath Of Allegiance" were eligible to vote.

1867 Voter Registration Lists. Available on self-service microfilm. This series was created in accordance with an act passed on March 2, 1867, "to provide for a more efficient government of the rebel States," and particularly to extend suffrage to the millions of freedmen across the south.

All adult black and white males who had sworn an oath of loyalty to the United States were eligible to register to vote.

Included is the person's name, race, length of residence in the state, county and precinct, the book and page where his oath is recorded, naturalization information, and reasons for rejecting some registrants. Arranged alphabetically by county, thereunder chronologically by date of registration.