James K. Polk

Polk became Speaker in December 1835, the only person to serve as both Speaker and president, following Jackson's political maneuvering.

Expansionist Southern Democrats blocked Van Buren's nomination at the 1844 Democratic National Convention, leading to Polk's emergence as a compromise candidate.

Henry Clay won the Whig presidential nomination unanimously, positioning himself as the leading contender against the Democrats.

Clay released the Alabama Letter on July 27, 1844, addressing Texas annexation and slavery expansion.

Polk defeated Clay in the general election, with voting occurring between November 1 and December 4, 1844.

James K. Polk was sworn in as the 11th President on March 4, 1845, at the U.S. Capitol, becoming the youngest president to that point.

Polk delivered his first annual message to the 29th Congress on December 2, 1845, calling for strict enforcement of the Monroe Doctrine and westward expansion.

Texas voters approved the annexation ordinance and a constitution endorsing slavery on October 13, 1845, following the Texas Congress's acceptance of the U.S. joint resolution.

President Polk signed the joint resolution admitting Texas as the 28th state on December 29, 1845, bypassing a territorial phase.

Texas relinquished sovereignty to the United States at the inauguration of Governor James Henderson on February 19, 1846.

The Oregon Treaty was signed in Washington, D.C., on June 15, 1846, ending joint occupation and establishing the 49th parallel as the boundary.

Mexican forces attacked a U.S. patrol in the disputed territory between the Nueces River and the Rio Grande, sparking the war.

Taylor defeated Mexican forces in the first major battle of the war.

The United States formally declared war on Mexico following the initial hostilities.

Anson Jones lowered the Republic of Texas flag and watched the US Stars and Stripes raised for the first time on Texas soil.

Texas relinquished its sovereignty to the United States at the inauguration of Governor James Henderson on February 19, 1846.

Both houses of Congress complied with President Polk's call to notify Britain of ending the joint occupation on April 23, 1846; the specific date of the House vote is not stated in the passages.

The 30th Congress convened in Washington, D.C., on March 4, 1847, for a two-year term during the Polk administration.

Frémont retired to California, establishing a ranch at Las Mariposas after the court-martial.

Frémont was convicted of military misconduct on January 31, 1848, in Washington, D.C., after being ordered to stand trial.

Congress passed the Act to Establish the Territorial Government of Oregon on August 14, 1848, creating the organized incorporated territory.

The Treaty of Guadalupe Hidalgo was signed on February 2, 1848, ending the Mexican–American War. U.S. envoy Nicholas Trist and Mexican representatives finalized the agreement at the Basilica of Guadalupe.

The two countries exchanged ratifications of the treaty on May 30, 1848, including a three-article protocol to explain amendments. This formalized the end of the war.