Timeline of Missouri History: 1930-1949
| 1931 | A bill creating the Missouri State Highway Patrol was signed by Governor Henry S. Caulfield (Apr. 24) | |
| 1931 | Bagnell Dam was completed, forming the Lake of the Ozarks, one of the largest artificial lakes in the world with approximately 1400 miles of shoreline |  President Truman and Winston Churchill in Fulton, Mo., 1945 Gerald Massie Collection |
| 1933 | William Rockhill Nelson Gallery of Art, was opened to the public in Kansas City | |
| 1936 | Thomas Hart Benton painted A Social History of Missouri in the State Capitol Building's House Lounge | |
| 1937 | The first Missouri Conservation Commission was appointed (Jul. 1) | |
| 1938 | The United States Supreme Court handed down its decision in the Lloyd Gaines case. The court struck a blow to Missouri’s "separate but equal" laws, stating that in the absence of an equal law school for black students, Gaines should be admitted to the University of Missouri law school (Dec. 12) | |
| 1939 | Kansas City "Boss" Tom Pendergast was sentenced to fifteen months in the federal penitentiary for income tax evasion (May 22) | |
| 1939 | The McDonnell Aircraft Corporation was organized by J.S. McDonnell; it merged with Douglas to form McDonnell Douglas Aircraft Corporation in 1967 | |
| 1940 | The Ellis Fischel State Cancer Center was opened in Columbia, becoming the first state-owned and operated hospital west of the Mississippi River devoted exclusively to the care of cancer patients | |
| 1945 | The Missouri Supreme Court handed down its decision in the Kraemer v. Shelley St. Louis housing segregation case | |
| 1945 | Missouri’s fourth, and current, Constitution became effective (Mar. 30) | |
| 1945 | U.S. Vice President Harry S Truman, from Independence, became President upon the death of Franklin Delano Roosevelt (Apr. 12) | |
| 1945 | Japan signed documents of surrender ending World War II in the Pacific on the deck of the USS Missouri (Sept. 2) | |
| 1946 | Winston Churchill, former Prime Minister of England, delivered his "Iron Curtain" speech at Fulton’s Westminster College (Mar. 5) | |
| 1948 | President Harry S Truman elected to the Presidency | |