What event directly caused the United States to join WWII?

The attack of pearl Harbor in Hawaii.

Explanation:

This is because some of their goods and things were in pearl harbor.

federal appellate courts are called courts of appeals. cases can be further appealed to the u.s. supreme court. cases are heard for the first time in a trial court. if either party disagrees with the decision in the trial court, they can appeal, asking a higher court to review the decision.