What would become the US States of California, Arizona, Nevada, Utah and New Mexico plus other minor concessions.
Mountain men
Early members of the Church of Jesus Christ of Latter-day Saints (commonly called the "Mormon" church) founded many cities and towns, the majority of which are still thriving today. These towns are located in the mid-west and western United States, as well as a handful in Canada and Mexico. You can find these early Mormon cities in western Illinois, southern Wisconsin, western Missouri, southern Idaho, northern Arizona, eastern Nevada, nearly the entire state of Utah, and scattered throughout California, southern Canada, and northern Mexico. In fact, there are so many early Mormon towns throughout the western United States that the I-15 corridor, (an interstate from Idaho through southern California) is commonly referred to as the "Mormon Curtain."
Immigrant Aide Society
They didn't want let let slavery spread to the western territories
Abraham Lincoln, because it underact the gains made by the 1860 election
The Act allowed for the creation of new slave-states, if the local population voted for it.
A new territory, Kansas, would likely become a slave state.
A new territory, Kansas, would likely become a slave state