By the 18th century, the Spanish Empire started spreading itself too thin. Before their crusades sent them off the peninsula in 1492, they only occupied a modest 300,000 sq. miles. During the height of their kingdom in 1810, they would add nearly 5 million more to their jurisdiction. Not only did their enemies and the marginalized castes in America begin to take notice, but so did their friends. The first to strike was Napoleon, who turned on his ally and began a chain reaction that would affect the boundaries of El Paso del Norte for over 150 years.
Despite popular belief, Spain did not see Mexico as a completely sovereign country in 1821. But because of the Plan of Iguala, Criollos were allowed to enterprise more freely. This could not have happened at a more opportune time. In May of 1824, after a couple years of foundational work, the first trade caravan from Missouri landed in Santa Fe –– before continuing on to Chihuahua, Sonora, and back by September. In four short months, the beginning of an international trade route was laid.
In the years that followed, trading amongst the area would become an economic boon. So much in fact, that the Mexican government would create the first customs house in El Paso del Norte –– as an effort to keep out illegal, untaxed, US goods. To put their success into perspective: in 1822, the value of trade between Santa Fe and Chihuahua was a meager $22k. By 1846, the value of trade would skyrocket to nearly a million dollars.
Despite Texas declaring independence in the east side of the state in 1835, El Paso del Norte was not involved for over a decade. When locals did get thrown into the mix, it wouldn’t even be “The Republic of Texas” fighting anymore. After decades of uncertainty on boundaries, the Union annexed Texas and decided to take up the fight against Mexico. The United States was barred from intervening prior to 1837, as Mexico was still technically owned by Spain.
Even though the US supported Mexico’s strive for independence (and even welcomed Bernardo Gutiérrez de Lara, to Washington DC in 1812), they knew it was an opportune time to strike. The United States had recently dealt with their own revolution –– which Spain helped them win –– and understood the difficulty in forming a country. They knew Mexico was vulnerable as they were still fighting amongst themselves, against Spain, France, and pro-slavery Texans.