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.
1856 Republican National Convention
On June 19, 1855, a small gathering of like-minded individuals met in Washington, D.C. where they passed a resolution noting the recent abrogation of "all compromises, real or imaginary" by the opening of Kansas Territory and Nebraska Territory to the possible institution of slavery. These proclaimed themselves the "Republican Association of Washington, District of Columbia" and passed a simple four plank platform including the demand that "There should be neither slavery nor involuntary servitude, except for the punishment of crime, in any of the Territories of the United States." A number of state organizations were soon established along similar lines and the Republican Party was effectively born.