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 between the late 1830s and 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. The Whig base of support was amongst entrepreneurs, professionals, Protestants (particularly evangelicals), and the urban middle class. It had much less backing from poor farmers and unskilled workers.

The party was hostile toward 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 United States and the 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 Whigs emerged in the 1830s in opposition to President Andrew Jackson, pulling together former members of the National Republican Party, the Anti-Masonic Party, and disaffected Democrats. The Whigs had some weak links to the defunct Federalist Party, but the Whig Party was not a direct successor to that party, and many Whig leaders, including Henry Clay, had aligned with the rival Democratic-Republican Party. In the 1836 presidential election, four different Whig candidates received electoral votes, but the party failed to defeat Jackson's chosen successor, Martin Van Buren. Whig nominee William Henry Harrison unseated Van Buren in the 1840 presidential election but died one month into his term. Harrison's successor, John Tyler, a former Democrat, broke with the Whigs in 1841 after clashing with Clay and other party leaders over economic policies such as the re-establishment of a national bank.

Clay clinched his party's nomination in the 1844 presidential election but was defeated by Democrat James K. Polk, who subsequently presided over the Mexican–American War. Whig nominee Zachary Taylor won the 1848 presidential election, but Taylor died in 1850 and was succeeded by Millard Fillmore. Fillmore, Clay, Daniel Webster, and Democrat Stephen A. Douglas led the passage of the Compromise of 1850, which helped to defuse sectional tensions in the aftermath of the Mexican–American War for a time. Nonetheless, the Whigs suffered a decisive defeat in the 1852 presidential election partly due to sectional divisions within the party. The Whigs collapsed following the passage of the Kansas–Nebraska Act in 1854, with most Northern Whigs eventually joining the anti-slavery Republican Party and most Southern Whigs joining the nativist American Party and later the Constitutional Union Party. The last vestiges of the Whig Party faded away after the start of the American Civil War, but Whig ideas remained influential for decades. During the Lincoln Administration, ex-Whigs dominated the Republican Party and enacted much of their American System. Presidents Abraham Lincoln, Rutherford B. Hayes, Chester A. Arthur, and Benjamin Harrison were Whigs before switching to the Republican Party, from which they were elected to office. It is considered the primary predecessor party of the modern-day Republicans.