1984 United States presidential election in Missouri

The 1984 United States presidential election in Missouri took place on November 6, 1984. All 50 states and the District of Columbia, were part of the 1984 United States presidential election. Voters chose 11 electors to the Electoral College, which selected the president and vice president of the United States.

Missouri was won by incumbent United States President Ronald Reagan of California, who was running against former Vice President Walter Mondale of Minnesota. Reagan ran for a second time with Vice-President George H. W. Bush of Texas, and Mondale ran with Representative Geraldine Ferraro of New York, the first major female candidate for the vice presidency.

The presidential election of 1984 was a perfectly partisan election in Missouri, with 100% of the electorate voting for either the Democratic or the Republican nominee, as only those two appeared on the ballot. Accordingly, every county gave either Mondale or Reagan an outright majority: five (including the county-equivalent of the city of St Louis) gave Mondale a majority; the rest gave Reagan one. Reagan's strongest performance was in Gasconade County, which gave him 80.54% of its ballots; Mondale's was in the city of St Louis, which gave him 64.80%. Missouri weighed in for this election as 2 percentage points more Republican than the national average. Reagan won the state in a landslide, amassing over 60% of the vote, slightly more than his national vote share. Republicans would not win the state again by double digits until 2016.

Reagan performed particularly strongly in its largest county or county-equivalent, suburban St Louis County (which does not include the city of St Louis), where he got 64% of the vote. He also got over 2/3 of the vote in the Show-Me State's fourth-largest county, historically Republican Greene County (home of Springfield). Mondale scored a strong win in the city of St Louis, where he got 64.8%, and eked out a narrow victory in Jackson County, home of Kansas City. However, he could not match Reagan in rural and small-town Missouri; aside from Jackson County and the city of St Louis, Mondale had only three other wins in Missouri's counties and county-equivalents, with his only convincing win being in the historically secessionist and highly unionized Lead Belt county of Reynolds County (he also narrowly won Oregon and Mississippi Counties). Reagan became the first Republican nominee to sweep Missouri's 'Little Dixie' region, as he became the first Republican ever to carry Monroe County. This feat was repeated by George W. Bush in 2004 (and, excluding Boone County, home to the University of Missouri, by every subsequent Republican nominee as of 2020).

Counties that flipped from Democratic to Republican

 * Boone
 * Buchanan
 * Dunklin
 * Howard
 * Iron
 * Monroe
 * New Madrid
 * Pemiscot
 * Ralls
 * Ray
 * Ste Genevieve
 * Shannon