The U.s tried to remain neutral however, little things the opposing sides did began to change their stance. Britain propaganda, the sinking of ships by German U-boats, the final thing that pushed them over the edge was the "Zimmerman" note. A note that tried to get Mexico to declare war on the U.s.
The latin american didn’t support them
When European settlers came over to the New World, they brought many diseases with them that the Native Americans had no immunity to. For this reason, they started dying from sicknesses and decrease their numbers by the millions.