Final answer:
The long-term outcome was a growth in political tensions between the U.S. and Mexico, heightened by land disputes and slavery debates post the Mexican-American War.
Step-by-step explanation:
The long-term result of the developments described is (a) the growth of political tensions between the United States and Mexico. Westward expansion and the aftermath of the Mexican-American War led to increased hostilities, land dispossession, and political disenfranchisements of the Hispanic population in Texas and California.
In addition, the war and the subsequent Mexican Cession triggered fierce debates over the extension of slavery in United States territories, which eventually escalated into the Civil War.The Mexican-American War and the acquisition of new territory resulted in resentment from Mexico and Latin America towards the United States. The tensions between the American and Mexican populations of Texas and California also increased as Hispanics were pushed out of the dominant society. These political tensions between the United States and Mexico persisted in the long run.