Merrill Monroe Jensen (1905–1980) was an American historian whose research and writing focused on the ratification of the United States Constitution. His historical interpretations are generally considered to be of the "Progressive School" of American history, the most famous exponent of which was Charles A. Beard. Jensen served as a professor of history at both the University of Washington (1935–1944), where he was editor of Pacific Northwest Quarterly, and the University of Wisconsin–Madison (1944–1976).
Born in Elkhorn, Iowa, Jensen took a job as a teacher in a one-room schoolhouse in South Dakota upon graduating from high school. In 1929, he earned a bachelor's degree at the University of Washington. He completed a Ph.D. at the University of Wisconsin–Madison in 1934. Except for a short stint as a historian for the Army Air Corps in 1944, his career was spent at his undergraduate and graduate alma maters. He was named to a limited-term appointment as Harmsworth Professor of American History at Oxford University in 1949.
He and his wife, Genevieve Margaret Privet, had one daughter. He died in Madison, Wisconsin, on January 30, 1980.
His early scholarship challenged the "consensus" interpretation of the Constitutional ratification process, arguing that the Articles of Confederation were a better expression of genuine democratic values than was the Constitution. The replacement of the Articles with the Constitution, Jensen argued, created a system of government that minimized the influence of radical democracy rooted in local politics. From his reading of the documentary evidence, he identified deep ideological conflicts among Americans at the time of the ratificaton. His later scholarship focused heavily on primary documents themselves, and he edited a number of substantial document collections, including the Documentary History of the First Federal Elections, 1788-1790 (launched in 1976 and completed in 1989 by his students Robert A. Becker and Gordon denBoer) and the Documentary History of the Ratification of the Constitution and the Bill of Rights, 1787-1791, (launched in 1976 and as of 1 January 2010 filling 21 of a projected 31 volumes).
- The Articles of Confederaton: An Interpretation of the Social-Constitutional History of the American Revolution, 1774-1781 (1940)
- The New Nation: A History of the United States during the Confederation, 1781-1789 (1950)
- Founding of a Nation: A History of the American Revolution, 1763-1776 (1968)
- The American Revolution within America (1974)
- Regionalism in America (1951)
- English Historical Documents, Volume IX, American Colonial Documents to 1776 (1955)
- The Making of the American Constitution (1964)
- Tracts of the American Revolution, 1763-1776 (1967)
- The Documentary History of the First Federal Elections, Volume I, 1788-1790 (1976), edited with Robert A. Becker.
- The Documentary History of the Ratification of the Constitution, Volume I: Constitutional Documents and Records, 1776-1787 (1976), edited with John P. Kaminski and Gaspare J. Saladino.
- The Documentary History of the Ratification of the Constitution, Volume II: Ratification by the States: Pennsylvania (1976), edited with John P. Kaminski and Gaspare J. Saladino.
- David S. Lovejoy, "Merrill Monroe Jensen," Proceedings of the Massachusetts Historical Society, Vol. 92 (1980), pps. 140-143.
- Stephen E. Patterson, "Interested Parties: Merrill Jensen and the Documentary History of Ratification," The William and Mary Quarterly, Vol. 59, No. 3 (July 2002), pps. 776-786
- "Center for the Study of the American Constitution". Retrieved 29 Sep 2014.