What was a significant Texas-related concern leading to the Mexican-American War?

The significant Texas-related concern leading to the Mexican-American War was primarily centered around disputes over Texas borders with Mexico. After Texas declared independence from Mexico in 1836 and later annexed by the United States in 1845, tensions erupted because Mexico did not recognize Texas's independence. The U.S. and Mexico had differing views on where the border should be drawn, with the United States claiming the Rio Grande as the border, while Mexico insisted it was further north at the Nueces River. This fundamental disagreement over territorial boundaries contributed to the outbreak of the war in 1846.

Understanding this context reveals the complexities of U.S.-Mexican relations at the time, as Mexico viewed the annexation and subsequent U.S. claims over Texas as acts of aggression, prompting them to engage in military action that escalated into the war.