Slavery in the United States in the context of "Slave states and free states"

The Republican Party, also known as the Grand Old Party (GOP), is a conservative and right-wing political party in the United States. It emerged as the main rival of the Democratic Party in the 1850s, and the two parties have dominated American politics since then.

The Republican Party was founded in 1854 by anti-slavery activists opposing the Kansas–Nebraska Act and the expansion of slavery into U.S. territories. It rapidly gained support in the North, drawing in former Whigs and Free Soilers. Abraham Lincoln's election in 1860 led to the secession of Southern states and the outbreak of the American Civil War. Under Lincoln and a Republican-controlled Congress, the party led efforts to preserve the Union, defeat the Confederacy, and abolish slavery. During the Reconstruction era, Republicans sought to extend civil rights protections to freedmen, but by the late 1870s the party shifted its focus toward business interests and industrial expansion. In the late 19th and early 20th centuries, it dominated national politics, promoting protective tariffs, infrastructure development, and laissez-faire economic policies, while navigating internal divisions between progressive and conservative factions. The party's support declined during the Great Depression, as the New Deal coalition reshaped American politics. Republicans returned to national power with the 1952 election of Dwight D. Eisenhower, whose moderate conservatism reflected a pragmatic acceptance of many New Deal-era programs.

The Mexican–American War, also known in the United States as the Mexican War and in Mexico as the United States intervention in Mexico, (April 25, 1846 – February 2, 1848) was an invasion of Mexico by the United States. It followed the 1845 American annexation of Texas, which Mexico still considered its territory because it refused to recognize the Treaties of Velasco, signed by President Antonio López de Santa Anna after he was captured by the Texian Army during the 1836 Texas Revolution. The Republic of Texas was de facto an independent country, but most of its Anglo-American citizens who had moved from the United States to Texas after 1822 wanted to be annexed by the United States.

Sectional politics over slavery in the United States had previously prevented annexation because Texas would have been admitted as a slave state, upsetting the balance of power between Northern free states and Southern slave states. In the 1844 United States presidential election, Democrat James K. Polk was elected on a platform of expanding U.S. territory to Oregon, California (also a Mexican territory), and Texas by any means, with the 1845 annexation of Texas furthering that goal. However, the boundary between Texas and Mexico was disputed, with the Republic of Texas and the U.S. asserting it to be the Rio Grande and Mexico claiming it to be the more-northern Nueces River. Polk sent a diplomatic mission to Mexico in an attempt to buy the disputed territory, together with California and everything in between for $25 million (equivalent to $798 million in 2024), an offer the Mexican government refused. Polk then sent a group of 80 soldiers across the disputed territory to the Rio Grande, ignoring Mexican demands to withdraw. Mexican forces interpreted this as an attack and repelled the U.S. forces on April 25, 1846, a move which Polk used to convince the Congress of the United States to declare war.

Millard Fillmore (January 7, 1800 – March 8, 1874) was the 13th president of the United States, serving from 1850 to 1853. He was the last president to be a member of the Whig Party while in the White House, and the last to be neither a Democrat nor a Republican. A former member of the U.S. House of Representatives, Fillmore was elected vice president in 1848, and succeeded to the presidency when Zachary Taylor died in 1850. Fillmore was instrumental in passing the Compromise of 1850, which led to a brief truce in the battle over the expansion of slavery.

Fillmore was born into poverty in the Finger Lakes area of upstate New York. He had little formal schooling, but studied to become a lawyer. Fillmore became prominent in the Buffalo area as an attorney and politician, and was elected to the New York Assembly in 1828 and the House of Representatives in 1832. Fillmore initially belonged to the Anti-Masonic Party, but became a member of the Whig Party as it formed in the mid-1830s. He was a rival for the state party leadership with Thurlow Weed and his protégé William H. Seward. Throughout his career, Fillmore declared slavery evil but said it was beyond the federal government's power to end it. Conversely, Seward argued that the federal government had a role to play. Fillmore was an unsuccessful candidate for Speaker of the U.S. House of Representatives when the Whigs took control of the chamber in 1841, but was made chairman of the Ways and Means Committee. Defeated in bids for the Whig nomination for vice president and for New York governor in 1844, Fillmore was elected Comptroller of New York in 1847, the first to hold that post by election.

The Democratic Party is a liberal political party in the United States. Sitting on the center to center-left of the political spectrum, it is the world's oldest active political party, having been founded in 1828. Its main rival is the conservative Republican Party, and since the 1850s both have dominated American politics.

It initially supported Jacksonian democracy, agrarianism, and geographical expansionism, while opposing a national bank and high tariffs. Democrats won six of the eight presidential elections from 1828 to 1856, losing twice to the Whigs. In 1860, the party split into Northern and Southern factions over slavery. The party remained dominated by agrarian interests, contrasting with Republican support for the big business of the Gilded Age. Democratic candidates won the presidency only twice between 1860 and 1908 though they won the popular vote two more times in that period. During the Progressive Era, some factions of the party supported progressive reforms, with Woodrow Wilson being elected president in 1912 and 1916.

The Kansas–Nebraska Act of 1854 (10 Stat. 277) was a territorial organic act that created the territories of Kansas and Nebraska. It was drafted by Democratic Senator Stephen A. Douglas, passed by the 33rd United States Congress, and signed into law by President Franklin Pierce. Douglas introduced the bill intending to open up new lands to develop and facilitate the construction of a transcontinental railroad. However, the Kansas–Nebraska Act effectively repealed the Missouri Compromise of 1820, stoking national tensions over slavery and contributing to a series of armed conflicts known as "Bleeding Kansas".

The United States had acquired vast amounts of land in the 1803 Louisiana Purchase, and since the 1840s, Douglas had sought to establish a territorial government in a portion of the Louisiana Purchase that was still unorganized. Douglas's efforts were stymied by Senator David Rice Atchison of Missouri and other Southern leaders who refused to allow the creation of territories that banned slavery; slavery would have been banned because the Missouri Compromise outlawed slavery in the territory north of latitude 36° 30′ north (except for Missouri). To win the support of Southerners like Atchison, Pierce and Douglas agreed to back the repeal of the Missouri Compromise, with the status of slavery instead decided based on "popular sovereignty". Under popular sovereignty, the citizens of each territory, rather than Congress, would determine whether slavery would be allowed.

The Whig Party was a mid-19th century political party in the United States. Alongside the Democratic Party, it was one of two major parties from the late 1830s until the early 1850s and part of the Second Party System. As well as four Whig presidents (William Henry Harrison, John Tyler, Zachary Taylor, and Millard Fillmore), other prominent members included Henry Clay, Daniel Webster, Rufus Choate, William Seward, John J. Crittenden, and John Quincy Adams (whose presidency ended prior to the formation of the Whig Party). The Whig base of support was amongst entrepreneurs, professionals, Protestant Christians (particularly Evangelicals), the urban middle class, and nativists.

The party was hostile towards the ideology of "manifest destiny", territorial expansion into Texas and the Southwest, and the Mexican–American War. It disliked presidential power, as exhibited by Andrew Jackson and James K. Polk, and preferred congressional dominance in lawmaking. Members advocated modernization, meritocracy, the rule of law, protections against majority rule, and vigilance against executive tyranny. They favored an economic program known as the American System, which called for a protective tariff, federal subsidies for the construction of infrastructure, and support for a national bank. The party was active in both the Northern and Southern United States and did not take a firm stance on slavery, but Northern Whigs tended to be less supportive than their Democratic counterparts.

The Free Soil Party, also called the Free Democratic Party or the Free Democracy, was a political party in the United States from 1848 to 1854, when it merged into the Republican Party. The party was focused on opposing the expansion of slavery into the western territories of the United States. The 1848 presidential election took place in the aftermath of the Mexican–American War and debates over the extension of slavery into the Mexican Cession. After the Whig Party and the Democratic Party nominated presidential candidates who were unwilling to rule out the extension of slavery into the Mexican Cession, anti-slavery Democrats and Whigs joined with members of the Liberty Party (an abolitionist political party) to form the new Free Soil Party. Running as the Free Soil presidential candidate, former President Martin Van Buren won 10.1 percent of the popular vote, the strongest popular vote performance by a third party up to that point in U.S. history.

Though Van Buren and many other Free Soil supporters rejoined the Democrats or the Whigs after the 1848 election, Free Soilers retained a presence in Congress over the next six years. Led by Salmon P. Chase of Ohio, John P. Hale of New Hampshire, and Charles Sumner of Massachusetts, the Free Soilers strongly opposed the Compromise of 1850, which temporarily settled the issue of slavery in the Mexican Cession. Hale ran as the party's presidential candidate in the 1852 presidential election, taking just under five percent of the vote. The 1854 Kansas–Nebraska Act repealed the long-standing Missouri Compromise and outraged many Northerners, contributing to the collapse of the Whigs and spurring the creation of a new, broad-based anti-slavery Republican Party. Most Free Soilers joined the Republican Party, which emerged as the dominant political party in the United States in the Third Party System (1856–1894).

The Thirteenth Amendment (Amendment XIII) to the United States Constitution abolished slavery and involuntary servitude, except as punishment for a crime. The amendment was passed by the Senate on April 8, 1864, by the House of Representatives on January 31, 1865, and ratified by the required 27 of the then 36 states on December 6, 1865, and proclaimed on December 18, 1865. It was the first of the three Reconstruction Amendments adopted following the American Civil War.

President Abraham Lincoln's Emancipation Proclamation, effective on January 1, 1863, declared that the enslaved in Confederate-controlled areas (and thus almost all slaves) were free. When they escaped to Union lines or federal forces (including now-former slaves) advanced south, emancipation occurred without any compensation to the former owners. Texas was the last Confederate slave state, where enforcement of the proclamation was declared on June 19, 1865. In the slave-owning areas controlled by Union forces on January 1, 1863, state action was used to abolish slavery. The exceptions were Kentucky and Delaware, where chattel slavery and indentured servitude were finally ended by the Thirteenth Amendment in December 1865.