In the 1890s, Cuba wanted to get their freedom from Spain. People like Jose Marti petitioned Americans to side with the Cubans and the poor treatment they were receiving from Spain. Also, there was a lot of support in the newspapers called "yellow journalism" where American people were sympathizing with the cause to go against Spain in war. This especially was true with a man nicknamed "The Butcher", Valeriano Weyler, who was a military leader from Spain placed in Cuba to put people in concentration camps.
As a result, America felt a strong sense of patriotism and business reasons to go to war with Spain. After the <em>USS Maine</em> exploded, the United States declared war on Spain.
A similar situation happened in the Philippines, where Spain had a high influence and America did want to free the Philippines from Spain, but then also had their own agenda to take over the Philippines, as it was in a strategic location in the Pacific for trade.
Jonathan Edwards, George Whitefield, John Calvin, and Jon Wesley
African Americans left their low paying jobs as agricultural laborers and domestic servants in the south to work in the high paying jobs in meatpacking, shipyards, and steel mills they found in the north.
A second reason was to escape the segregation they experienced in the south.
Grievances, hope this helps.