The United States obtained full control of the Panama Canal in 1903 through the Hay-Bunau-Varilla Treaty with Panama after sending warships to help Panama gain independence from Columbia. The treaty stipulated that, for a one-time payment of $10 million, a yearly rental fee of $250,000 and the promise of U.S. protection, Panama granted the United States perpetual control of the canal itself and five miles of land on either side.
The United States first planned to build a canal from the Atlantic to the Pacific through Nicaragua, but the attempt never got beyond negotiations. Meanwhile, the French attempted to build a canal across Panama, but after seven years of effort and the loss of 20,000 lives, the project went bankrupt. In 1902, the United States bought the French-owned canal territory for $40 million. In 1903, the United States and Columbia signed the Hay-Herran Treaty, with terms similar to the subsequent treaty with Panama, but the Colombian senate refused to ratify it. President Theodore Roosevelt assured the Panamanians that, if they revolted and declared their independence, the U.S. Navy would back them up. In return, the new Panamanian government approved the treaty with the United States.
The United States held full control of the Panama Canal and the Canal Zone until 1979, when it turned over most of the Canal Zone and partial control of the canal to the government of Panama. On Dec. 31, 1999, the United States withdrew completely from the canal and Canal Zone and turned over operations to Panama.