By helping the Panamanian's overthrow the Columbian government.
In recent years the U.S. has signed two treaties turning over the Panama Canal to the republic of Panama in the year 2000. Making the Panama Canal bigger is still needed.
Why they wanted it built: The U.S. wanted to avoid going around South America and insure less time for U.S. Naval ships to travel and protect U.S. possessions around the world
