It has been claimed that the TONA became part of the U.S. Constitution—indeed many printings of the Constitution during the 19th century erroneously included it as a Thirteenth Amendment. Perhaps this misunderstanding could be traced to the mistaken belief that both houses of South Carolina's legislature had acted favorably upon the TONA when, evidently, only one of its houses did so. It can also be attributed to the misimpression that both houses of Virginia's legislature had adopted the TONA—again, when apparently only one of its houses did so. In general, 19th century procedures for communicating and recording the ratifications of constitutional amendments were haphazard and some printings of the Constitution included the amendment out of uncertainty. Many other 19th century printings omit it.
There is a further misapprehension that the TONA was—at all stages in the ratification process—just one state's adoption shy of being incorporated into the United States Constitution.
When the TONA was offered by the Congress to the state legislatures on May 1, 1810, the approval of 13 of them would indeed have been required. However, with the addition of Louisiana into the Union on April 30, 1812, that threshold increased to 14 state approvals. Louisiana's statehood commenced after the Massachusetts ratification of the TONA, but prior to the New Hampshire ratification of it. Then, when Indiana was admitted on December 11, 1816, the bar was raised up to 15 approvals needed to ratify the TONA. Although the admission of Mississippi on December 10, 1817, did not increase the numerical requirement, the entry of Illinois on December 3, 1818, did elevate that minimum to 16 state adoptions necessary for the TONA to be incorporated into the Constitution.
The term "Thirteenthers" is sometimes used to refer to those who mistakenly believe this amendment was ratified or to those who would like to see ratification of this proposed amendment.
Not until 1865 was a proposed Thirteenth Amendment adopted. That amendment abolished slavery throughout the United States.