According to the panama canal treaty signed by president carter, it says that

The treaty recognized Panama as the territorial sovereign in the Canal Zone but gave the United States the right to continue operating the canal until December 31, 1999.

Explanation:

On September 7, 1977, President Jimmy Carter and Panamanian leader Omar Torrijos signed the Panama Canal Treaty, which ceded U.S. control of the canal beginning in 2000 and guaranteed the neutrality of the waterway thereafter.

The treaties guaranteed that Panama would gain control of the Panama Canal after 1999, ending the control of the canal that the U.S. had exercised since 1903. The treaties are named after the two signatories, U.S. President Jimmy Carter and the Commander of Panama's National Guard, General Omar Torrijos.

i just did something on this guy a few days a go give me two minutes to find it in my notes.