What was the zimmerman note? why was the united states so upset by it?

It was a note from Germany to Mexico during World War 1 that said that if Mexico helped the Central Powers win the war by declaring war on the US, Germany would help Mexico regain territory Mexico had lost in the Mexican-American War. It was found out by the United States and was one of the reasons they joined the war.

The frequently used source of renewable energy in the U.S and Canada is the hydroelectric power.