Final answer:
The Mexican War of 1846 concluded with the Treaty of Guadalupe Hidalgo, which resulted in the extensive territorial expansion of the United States and intensified debates over slavery, culminating in a push towards the Civil War.
Step-by-step explanation:
The overall end result of the Mexican War of 1846, also known as the Mexican-American War, was the signing of the Treaty of Guadalupe Hidalgo in February 1848. This treaty had significant implications, including the confirmation of the United States' title to Texas and the cession of a vast amount of territory to the United States, totaling some 525,000 square miles. As a consequence, Mexico lost more than half of its territorial land mass, resulting in the expansion of U.S. holdings and furthering the ideology of Manifest Destiny.
The ceded lands from the Mexican Cession eventually became all or parts of the U.S. states of California, Arizona, New Mexico, Texas, Utah, Nevada, Colorado, Wyoming, and Kansas. The United States agreed to pay Mexico $15 million and assume American claims against Mexico amounting to about $3,250,000. Additionally, in 1853, the Gadsden Purchase finalized the present border between the United States and Mexico with the purchase of Arizona's Mesilla Valley.
This acquisition of territory also provoked a heated debate regarding the expansion of slavery, leading to heightened sectional tensions that contributed to the onset of the American Civil War.