Territorial Expansion and Sectional Crisis

Neighbors are never going to always fully get along and agree with each other. The United States and Mexico are neighbors when it came to where their land is located and they had their fair share of issues. Mexico and the United States shared a border which meant there was going to be problems between them. The United States had finally declared war on Mexico in 1846 from a buildup of different issues. There were many factors that impacted the United State’s decision to declare war on Mexico. These decisions included the idea of Manifest Destiny, the Rio Grande boundary dispute, and Slidell’s mission. All of these things were very important when it came to declaring war on Mexico or not, but they helped put the United States over the edge. Manifest Destiny was the belief during the 1800s that the United States was destined to expand across the continent, from Atlantic coast to Pacific Coast. Americans wanted to own all the land across the continent because that is why they believed God had created the land like that. In addition, there were economic depressions in 1818 and 1839 that lead many people searching for land in frontier areas. In many cases frontier land was much more inexpensive or even free so they wanted to take advantage of the land. Americans also saw this as a good opportunity to promote and expand commerce and trade by building ports on the west coast. The original US-Mexico border was defined by the Sabine River north from the Gulf of Mexico to the 32nd parallel north (32°N), then due north to the Red River, west along the Red River to the 100th meridian west (100°W), due north to the Arkansas River, west to its headwaters, north to the 42nd parallel north (42°N), and finally west along that parallel to the Pacific Ocean. In the 1800s, Mexico had owned much of the land out by the west coast. Mexico owned present-day California, Nevada, Utah and the rest of Colorado as well as most of northern New Mexico and Arizona, parts of the