What if the Mexican American War never happened?

There are various very different scenarios for this, for example: The Adams-Onís Treaty is never signed and the US-Spanish border remains indefinite. American settlers reach the East Texas cotton country, which becomes part of the USA without triggering major conflict, and the South has little reason to press on further. read more

In terms of politics, a lot came about as a result of the Mexican American war. Most of the Civil war's generals built their reputations in the Mexican American war. They tasted combat for the first time and learned from the mistakes of both the American and Mexican armies during that war. read more

When the war ended, the U.S. had acquired over 500,000 sq. miles of new land, including Texas and the Mexican territories that would eventually become the states of California, Arizona, New Mexico — and comprise significant parts of Colorado, Utah, Wyoming and Nevada. read more

On the other hand, if the American Rebellion had not happened, Britain might not have felt as much need to build an East of Suez Empire in the first place. Britain had already gained the dominant position in India in the Seven Years’ War, but that could easily be reversed or abandoned. read more