The party was born of hostility to slavery. Back in 1820, the US Congress had agreed the Missouri Compromise, under which Missouri entered the Union as a slave state, but slavery was forbidden anywhere else in the Louisiana Purchase north of 36º 30’. However, in 1854 the principle was threatened by the Kansas-Nebraska Act, under which the white inhabitants of the two territories were to decide by referendum whether slavery would be allowed there or not. There were numerous Americans in the northern states who disapproved of slavery, including many northern Whigs and Democrats as well as the Free Soilers, who had sprung from concern over the possible introduction of slavery in territory acquired from Mexico in the 1840s. With the slogan ‘Free soil, free speech, free labor and free men’, the Free Soil Party had run Martin Van Buren unsuccessfully for president in 1848.

Free Soilers now joined Whigs and northern Democrats to form a new, completely northern political party. The original impetus came from impromptu ‘anti-Nebraska’ meetings in the north-western states of Wisconsin and Michigan to discuss what to do if the Kansas-Nebraska Act passed. The meetings were not only opposed to slavery, but demanded the opening up of the West by small homesteaders and the building of railroads. In February a gathering in Ripon, Wisconsin, resolved to form a new party and a local lawyer named Alvan E. Bovay suggested the name Republican for its echoes of Thomas Jefferson. In Michigan there were meetings in Kalamazoo, Jackson and Detroit, and after the Act had passed in May, the new party was formally founded in Jackson in July. A leading figure was Austin Blair, a Free Soiler lawyer who was prosecuting attorney of Jackson County. He helped to draft the new party’s platform, was elected to the state senate in Republican colours that year and would become governor of Michigan in 1860.

In Illinois meanwhile, another lawyer, a Whig named Abraham Lincoln, had come out against slavery and the Kansas-Nebraska Act. In a speech at Peoria in October 1854 he said: ‘No man is good enough to govern another man without that other’s consent.’ He proclaimed that slavery was ‘a monstrous injustice’ and a breach of the Declaration of Independence and for a time he favoured transporting ex-slaves back to Africa. The new party quickly spread to the other northern states, where it displaced the Whigs as the principal opposition to the Democrats.

Slavery was not the only issue. Northerners often looked down on blacks, but dislike of slavery was part of belief in a United States in which every man was free to make himself a good life by his own efforts. Already in the 1854 elections the Republicans gained a majority in the House of Representatives. Two years later the party ran its first presidential candidate, the celebrated western explorer John C. Fremont, who carried eleven states. The 1860 party convention in Chicago chose Lincoln as its candidate with Hannibal Hamlin of Maine, a former Democrat, as his running mate. The northern and southern wings of the Democratic Party ran rival candidates, which let the Republicans in with the electoral votes of all the northern states. From then until 1932, of seventeen presidential elections the Republicans lost only four, two each to Grover Cleveland and Woodrow Wilson. No new political party has won an American presidential election since 1860.