USA HISTORY

Detailed explanation-1: -Until 1836, Texas had been part of Mexico, but in that year a group of settlers from the United States who lived in Mexican Texas declared independence. They called their new country the Republic of Texas, which was an independent country for nine years.

Detailed explanation-2: -In 1844, Congress finally agreed to annex Texas. On December 29, 1845, Texas entered the United States as a slave state, broadening the irrepressible differences in the United States over the issue of slavery and setting off the Mexican-American War.

Detailed explanation-3: -By its terms, Mexico ceded 55 percent of its territory, including the present-day states California, Nevada, Utah, New Mexico, most of Arizona and Colorado, and parts of Oklahoma, Kansas, and Wyoming.

Detailed explanation-4: -It stemmed from the annexation of the Republic of Texas by the U.S. in 1845 and from a dispute over whether Texas ended at the Nueces River (the Mexican claim) or the Rio Grande (the U.S. claim).