Before the U.S.S Maine exploded, Spain at the time, ruled over Guam, Puerto Rico and Cuba. In Cuba, the Spaniards kept control of the banks, the plantations and the government. Cubans were treated unfair, some were held as slaves and put into concentration camps. About 400,000 Cubans died in there. The U.S didn't think any of this was right. Plus the trades between Cuba and the United States have gone down by two-thirds so the U.S wanted to know what was happening.