The state of Texas has given the United States plenty to be excited for, including Dallas barbecue, the inspirations for "Friday Night Lights" and "Varsity Blues," UGK, Lone Star beer and the old Houston Oilers. (For the time being, we'll ignore the states lesser exports, like the Bush family and an upsetting obsession with firearms.) But before Texans could give back to the United States, they had to join the Union first, which they did on this day in 1845.
The Republic of Texas declared their independence from Mexico in 1836 following a bloody conflict. General Sam Houston, who lead the Texans to victory at San Jacinto, was elected president of the newly independent republic, but the citizens also supported entrance into the United States. So why did nearly a decade elapse before the deal was made? Texas remained a slave state, and though slavery remained a fixture in the United States (the 13th Amendment, which outlaws slavery, wouldn't be ratified until the close of the Civil War in 1865), Congress was reticent to admit new states that still held fast to slavery.
Despite the fact that Texas had declared its independence, Mexico still considered Texas its property, and once the U.S. annexed the area and made it into a state, the country launched the Mexican-American War, a bloody two year conflict that spread all over the southwestern U.S. and Mexico.