Panama Canal is not for sale, Panama's president says. What to know about the canal's history and status

President-elect Donald Trump has repeatedly suggested the United States take over the Panama Canal, a shipping waterway that cuts across Central America, unless fees for using the canal are lowered. 

Panama's leader shot back in a recent statement, saying the shipping waterway is not for sale. Since then, Trump has posted repeatedly about the canal. 

It's the latest in a series of similar statements from Trump, who recently suggested the United States take over Greenland, an idea he also floated during his first presidency. He's also joked about Canada being a U.S. state.