Final answer:
The Treaty of Guadalupe Hidalgo in 1848 ended the US-Mexican War, leading to Mexico ceding over half of its territory to the United States, including future states like California and Texas, and intensifying debates over slavery and Manifest Destiny.
Step-by-step explanation:
The period in the history of the Americas that came to an end with the US-Mexican War was a time when Mexico controlled vast territories in what is now the southwestern United States. The conclusion of this war is marked by the signing of the Treaty of Guadalupe Hidalgo in 1848.
This treaty confirmed the United States' claim to Texas and transferred over half of Mexico's territory—encompassing present-day California, Arizona, New Mexico, Texas, Utah, Nevada, Colorado, Wyoming, and Kansas—to the US, resulting in significant territorial expansion and furthering the concept of Manifest Destiny.
The immense land acquisition by the United States was not without consequences. Tensions rose between different populations in the new territories, and the question of extending slavery into these areas became an intensely debated issue. Ultimately, this period highlighted both the expansionist ambitions and the conflicts that would shape the future of the continent.