Answer:
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.
Step-by-step explanation: