Massachusetts Republican Party
The Massachusetts Republican Party was founded in 1854. Drawing together abolitionist and nativist anti-Catholic elements, it quickly became the dominant political force in the state and a powerful arm of the national Republican Party. Significant founding figures include Senator Charles Sumner, formerly of the Free Soil Party, and Speaker of the House Nathaniel Prentiss Banks, formerly of the American Party. 
At the time of the Republican Party's founding in 1854, all of Massachusetts's congressional representatives but Sumner were members of the nativist Know-Nothing Party. However, Banks's role as chairman of the 1856 Republican National Convention, his active support for the Republican presidential nominee John C. Frémont in 1856 and his focus on anti-slavery legislation as Speaker put him at odds with his party. Following the Democratic victory in the 1856 elections and the Dred Scott case in 1857, the national American Party organization collapsed, and most Northern members joined the nascent Republicans. In 1857, Banks ran as a Republican against incumbent Know-Nothing Governor Henry J. Gardner and won a decisive victory.
Mississippi Republican Party
In 1956, Wirt Adams Yerger, Jr., an insurance agent from Jackson, founded the modern Mississippi Republican Party and served as the first state chairman from 1956 until 1966. He was chairman of the Mississippi delegation to the Republican National Convention in 1956, 1960, and 1964. He was elected to a four-year term as chairman of the Southern Association of Republican State Chairman in 1960. In 2009, the central committee of the Mississippi Republican Party named Yerger Chairman Emeritus. The Mississippi Republican Party would grow in supporters with then President Dwight D. Eisenhower, who still twice lost the electoral votes of Mississippi. On September 24, 1960, Republican presidential candidate Richard Nixon campaigned in the state, the first time a presidential candidate had appeared in the state in more than a century. During the 1964 Republican National Convention Mississippi delegates would help nominate Barry Goldwater for President. Goldwater would go on to win 87 percent of the vote in Mississippi in the 1964 Presidential Election, the first time a Republican would win the state since the Reconstruction Era. Only once since 1956 has a non-Republican presidential candidate won the state of Mississippi, Jimmy Carter in the 1976 Presidential Election. In 1988, Republican Congressman Trent Lott would defeat Democratic Congressman Wayne Dowdy to replace retiring Senator John Stennis(D-MS).