Texas annexation in the context of "Territorial evolution of the United States"

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.

Texas (/ˈtɛksəs/ TEK-səss) is the most populous state in the South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the west, and an international border with the Mexican states of Chihuahua, Coahuila, Nuevo León, and Tamaulipas to the south and southwest. Texas has a coastline on the Gulf of Mexico to the southeast. Covering 268,596 square miles (695,660 km) and with over 31 million residents as of 2024, it is the second-largest U.S. state by both area and population. Texas is nicknamed the "Lone Star State" for the single star on its flag, symbolic of its former status as an independent country, the Republic of Texas.

Spain was the first European country to claim and control Texas. Following a short-lived colony controlled by France, Mexico controlled the land until 1836 when Texas won its independence, becoming the Republic of Texas. In 1845, Texas joined the United States of America as the 28th state. The state's annexation set off a chain of events that led to the Mexican–American War in 1846. Following victory by the United States, Texas remained a slave state until the American Civil War, when it declared its secession from the Union in early 1861 before officially joining the Confederate States on March 2. After the Civil War and the restoration of its representation in the federal government, Texas entered a long period of economic stagnation.

Presidential elections were held in the United States from November 1 to December 4, 1844. Democratic nominee James K. Polk narrowly defeated Whig Henry Clay in a close contest turning on the controversial issues of slavery and the annexation of the Republic of Texas. This is the only election in which both major party nominees served as Speaker of the House at one point, and the first in which neither candidate held elective office at the time.

President John Tyler's pursuit of Texas annexation divided both major parties. Annexation would geographically expand American slavery. It also risked war with Mexico while the United States engaged in sensitive possession and boundary negotiations with Great Britain, which controlled Canada, over Oregon. Texas annexation thus posed both domestic and foreign policy risks. Both major parties had wings in the North and the South, but the possibility of the expansion of slavery threatened a sectional split in each party. Expelled by the Whig Party after vetoing key Whig legislation and lacking a firm political base, Tyler hoped to use the annexation of Texas to win the presidency as an independent or at least to have decisive, pro-Texas influence over the election.

The Mexican Cession (Spanish: Cesión mexicana) is the territory that Mexico ceded to the United States in the Treaty of Guadalupe Hidalgo in 1848 after the Mexican–American War. It comprises the states of California, Texas, New Mexico, Utah, Nevada, and Arizona, and parts of Colorado, Oklahoma, Kansas, and Wyoming in the present-day Western United States. Consisting of roughly 529,000 square miles (1,370,000 km), not including Texas, the Mexican Cession was the third-largest acquisition of territory in U.S. history, surpassed only by the 827,000-square-mile (2,140,000 km) Louisiana Purchase of 1803 and the later 586,000-square-mile (1,520,000 km) Alaska Purchase from Russia in 1867.

Most of the ceded territory had not been claimed by the Republic of Texas following its de facto independence in the 1836 revolution. Texas had only claimed areas east of the Rio Grande. After annexation into the U.S. and admission as a state in 1845, Texas's southern and western boundaries with the Mexican state of Santa Fe de Nuevo México had not been defined by the U.S. Most of the ceded area was part of the Mexican province of Alta California (Upper California) while the southeastern strip east of the Rio Grande had been part of the state of Santa Fe de Nuevo México. Mexico had controlled the ceded territories with considerable local autonomy. After the Mexican War of Independence finished in 1821, the area had seen several revolts but the Mexican government sent few troops from central Mexico to suppress them. In 1846, U.S. President James K. Polk sent soldiers to occupy the disputed territory between the Nueces River and the Rio Grande, starting the Mexican–American War. At the war's outbreak, the U.S. conducted a naval landing on Mexico's northeastern coast on the Gulf of Mexico, and advanced into Nuevo México.

Stephen Arnold Douglas (né Douglass; April 23, 1813 – June 3, 1861) was an American politician and lawyer from Illinois. As a U.S. senator, he was one of two nominees of the badly split Democratic Party to run for president in the 1860 presidential election, which was won by Republican candidate Abraham Lincoln. Douglas had previously defeated Lincoln in the 1858 United States Senate election in Illinois, known for the pivotal Lincoln–Douglas debates. Earlier, Douglas was one of the brokers of the Compromise of 1850, which sought to avert a sectional crisis; to further deal with the volatile issue of extending slavery into the territories, Douglas became the foremost advocate of popular sovereignty, which held that each territory should be allowed to determine whether to permit slavery within its borders. This attempt to address the issue was rejected by both pro-slavery and anti-slavery advocates. Standing 5 feet 4 inches (1.63 m) tall, Douglas was nicknamed the "Little Giant" because he was short in physical stature but a forceful and dominant figure in politics.

Born in Brandon, Vermont, Douglas migrated to Jacksonville, Illinois, in 1833 to establish a legal practice. He experienced early success in politics as a member of the newly formed Democratic Party, serving in the Illinois House of Representatives and various other positions. He was appointed to the Supreme Court of Illinois in 1841. In 1843, he was elected to the U.S. House of Representatives and therefore resigned from the Supreme Court of Illinois. Douglas became an ally of President James K. Polk and favored the annexation of Texas and the Mexican–American War. He was one of four Northern Democrats in the House to vote against the Wilmot Proviso, which would have banned slavery in any territory acquired from Mexico.

John Parker Hale (March 31, 1806 – November 19, 1873) was an American politician and lawyer from New Hampshire. He served in the United States House of Representatives from 1843 to 1845 and in the United States Senate from 1847 to 1853 and again from 1855 to 1865. He began his congressional career as a Democrat, but helped establish the anti-slavery Free Soil Party and eventually joined the Republican Party.

Born in Rochester, New Hampshire, Hale established a legal practice in Dover, New Hampshire after graduating from Bowdoin College. Hale won election to the New Hampshire House of Representatives in 1832 and served as the United States Attorney for New Hampshire under President Andrew Jackson and President Martin Van Buren. He won election to the United States House of Representatives in 1842 but was denied the party's nomination in 1844 due to his opposition to the annexation of Texas. After losing his seat, he continued to campaign against slavery and won election to the Senate in 1846 as an Independent Democrat. In the Senate, he strongly opposed the Mexican–American War and continued to speak against slavery.

The Texas Army, officially the Army of the Republic of Texas, was the land force branch of the Texas Military Forces during the Republic of Texas. It descended from the Texian Army, which was established in October 1835 to fight for independence from Centralist Republic of Mexico in the Texas Revolution. The Texas Army was provisionally formed by the Consultation in November 1835; however, it did not replace the Texian Army until after the Battle of San Jacinto. The Texas Army, Texas Navy, and Texas Militia were officially established on September 5, 1836, in Article II of the Constitution of the Republic of Texas. The Texas Army and Texas Navy were merged with the United States Armed Forces on February 19, 1846, after the Republic of Texas became the 28th state of America.