What if the U. S. had not engaged in
the Spanish-American War?

If the US had not engaged in the Spanish-American war, the US would lose a sizeable part of land, most of it being fertile. As a result, the US may partake in the Spanish-American war at another time, but if this war never happens, the US economy would be a lot smaller (without California's fertile land and gold), and Mexico would most likely be a modern world power, instead of America. To dive even further into the possibilities of this, the Spanish-American war could happen, but Mexico would win.

Explanation:

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