Panama Canal
Colombia, France, and later the United States controlled the territory surrounding the canal during construction. The US continued to control the canal and surrounding Panama Canal Zone until the 1977 Torrijos–Carter Treaties provided for handover to Panama. After a period of joint American–Panamanian control, in 1999, the canal was taken over by the Panamanian government. It is now managed and operated by the government-owned Panama Canal Authority.
World War II by country
The small Panama Canal Zone was United States territory, and American forces from the U.S. Navy, U.S. Army, the USAAF (at Howard Air Force Base), and Colombian forces helped inside the Canal Zone, guarded the Panama Canal from both ends. This Canal provided the United States and its Allies with the ability to move warships and troops rapidly between the Atlantic Ocean and the Pacific Ocean. Since most of the American shipbuilding capability was on the East Coast and the Gulf of Mexico, the Canal was vital for moving new warships to the Pacific to fight the Imperial Japanese Navy