(imperialism and world war 1) What are some of the reasons for U. S. involvement and
interest in other countries and territories?

It's because America wants to hold a dominant power over the world

Explanation:

Some reasons for US involvement in world war 1 is because of the Zimmerman telegram, which was a telegram sent by a certain Author Zimmerman, to Mexico which asked it to invade America but before this telegram went to Mexico it was intercepted by London and then later on sent  to the US which was the reason why the US joined world war 1. Another reason could be the Lusitania which was sunken by a German U-Boat which swung American opinion to the Germans. The US really realized its power when it was able to defeat the Spanish empire, and it was called the Spanish-American war, which was the when one empire died and another was born. And they had interest in other countries and territories because, why not?  

these civilizations were located around fertile rivers, where they could produce an abundance of crops