How did the mexican-american war lead to greater sectionalism within the united states government?

New land was added to the US from the Treaty of Guadalupe Hidalgo and how to handle the new land created a deeper divide between the North and South.

The Southwest of the US to include Texas, Arizona, New Mexico, Nevada, Utah, part of Colorado and Wyoming, and California was added to the US ceded from Mexico.

This new land was desired by people in the South and West for different reasons. Southerners wanted new land to expand plantation and slave systems whereas people in the West and even in the North wanted the land to expand transportation and gain access to farm land, mines, and ranching lands. Northerners wanted to create a new plan for the land from preventing slavery in the land all together to all territories to decide for themselves. The compromises would not be enough to hold the concerns together and within fifteen years the Civil War would begin.