How many states ratified the 16th Amendment and which state provided the decisive ratification?
Executive summary
The Sixteenth Amendment was declared ratified when thirty-six state legislatures — three‑fourths of the forty‑eight states then in the Union — had approved it, and the Secretarial proclamation certified that threshold in 1913 [1] [2]. Contemporary records and standard legal histories identify Delaware as the state whose action completed the required thirty‑six ratifications, and the amendment was officially proclaimed in February 1913 [3] [4].
1. What “ratified” means and the numerical threshold that mattered
Under Article V of the Constitution an amendment becomes part of the Constitution when ratified by three‑fourths of the states; in 1913 that meant thirty‑six of the forty‑eight state legislatures had to approve the proposed Sixteenth Amendment, a threshold repeatedly cited in federal records and historical summaries [1] [5] [2].
2. The official count: thirty‑six states met the requirement
The Department of State proclamation and government reference works record that thirty‑six states had ratified the amendment by the time the Secretary certified its adoption, language echoed by the National Archives and Congress’s historical materials noting the declaration in February 1913 [4] [2] [1]. These official tallies — used in legal and archival practice — are the basis for saying the amendment was properly ratified and took effect.
3. Which state provided the decisive ratification: Delaware
Multiple commonly cited sources state that ratification was completed on February 3, 1913, with Delaware’s action counted as the thirty‑sixth approval, a fact reflected in standard histories and reference works summarizing the ratification sequence [3] [5]. The Secretary of State’s proclamation lists Delaware among the thirty‑six states whose legislatures had ratified and thereby constituted the required three‑fourths [4].
4. Certification and proclamation: the formal finishing touch
Although state legislatures cast the decisive votes, the formal administrative act that closed the tally was the Secretary of State’s proclamation certifying that the requisite number of state legislatures had ratified; that proclamation was issued in February 1913 and is the document historians point to when marking the amendment’s entry into force [4] [2].
5. Later ratifications and contested narratives
After the amendment took effect, additional states ratified it over time, bringing later tallies to higher totals (sources note forty‑two later ratifications in some summaries), but those subsequent approvals were not necessary to reach the three‑fourths threshold that made the amendment operative in 1913 [6] [3]. A small but persistent body of tax‑protester literature argues the amendment was never properly ratified, citing alleged procedural defects; courts and legal scholarship have repeatedly rejected those challenges and stated that the Secretary of State’s certification is conclusive and beyond review in ordinary litigation [7] [6].
6. Why the record matters today
The accepted historical and legal narrative — rooted in the Secretary of State’s proclamation, National Archives certification, and congressional records — holds that thirty‑six states ratified the Sixteenth Amendment by early February 1913 and that Delaware’s vote completed that count; that administrative and judicial posture underpins why challenges to the amendment’s validity have been unsuccessful in courts [4] [2] [7]. Where alternative claims exist, they rest on reinterpretations of state procedures rather than on a competing official federal count, and those claims have not displaced the archival and judicial record [7] [6].