Texas joined the United States of America on this date 177 years ago.

The Republic of Texas declared independence from Mexico in 1836 following the Texas Revolution. Nine years later, on December 29, 1845, Texas formally joined the Union as the 28th state.

Texas had applied for United States annexation in 1836 but was rejected by U.S. Secretary of State John Forsyth. The sovereign state of the Republic of Texas was then formed, and Sam Houston was elected as its president in September.

In 1841, John Tyler was inaugurated as President of the United States with the expressed intention of expanding the American empire. The annexation of Texas then became his “primary objective,” according to historian Edward Crapol.

Following unfruitful negotiations with Mexico and Great Britain, the Houston administration signed the Tyler-Texas treaty on April 12, 1844. The treaty annexed Texas to the United States as a territory and incorporated Texas citizens as citizens of the United States.

The State Department’s Office of the Historian explained that President Tyler’s efforts to establish the annexation treaty “caused Mexico to sever diplomatic relations with the United States.”

Lacking the necessary votes in the Senate, the treaty was defeated by a wide margin in June. Tyler tried once more before leaving office, and with the support of President-elect Polk, the joint resolution was passed by Congress on March 1, 1845.

Texas joined the Union as a slave state. Its statehood caused tension between the United States and Mexico, one of the primary factors that sparked the Mexican-American War (1846-1848).

Texas’ initial statehood was short-lived as it seceded from the Union in March 1861, joining the Confederate States of America at the beginning of the Civil War.

Following the defeat of the Confederacy and General Robert E. Lee’s surrender on April 9, 1865, in Appomattox, Virginia, the State of Texas was readmitted to the Union on March 30, 1870.