Panama Canal

Workers load concrete into buckets on flat-bed rail cars at a concrete plant in Gatun, Panama Canal. At the Gatun Locks on the Atlantic side of the canal, workers poured enough concrete to build a wall eight feet wide and 12 feet high for 133 miles.   (AFP/Getty Images)

U.S. President Theodore Roosevelt, fifth from the left, visits the Panama Canal area in 1906.   (AFP/Getty Images)

A train and steam shovels work on the Culebra Cut of the Panama Canal as workers dig their way toward the Atlantic coast.   (AFP/Getty Images)

Workers labor to create the Panama Canal in May 1913.   (AFP/Getty Images)

The ship S.S. Ancon in the Panama Canal on opening day in 1914, as seen from Cerro Luisa, looking north.   (AFP/Getty Images)

Panamanians take to the streets Nov. 3, 1999, in Panama City, Panama. The sign in the parade reads, “The Canal is Ours,” referring to the pending handover of the canal and all its operations to Panama from the United States on Dec. 31, 1999.   (Julio Martinez / Associated Press)

Presidents and leaders from several nations, including King Juan Carlos of Spain and former U.S. President Jimmy Carter, attend the official transfer of the Panama Canal Dec. 14, 1999.  (Rodrigo Arangua / AFP/Getty Images)

A ship passes through Gaillard Cut of the Panama Canal in 2000, when widening works were in progress.   (Tomas Munita / Associated Press)

The USS Iowa crosses the Panama Canal at Miraflores Lock on March 28, 2001. At 108.2 feet wide, the Iowa-class battleships are the largest vessels ever to scrape their way through the 110-foot-wide locks of the canal. They were designed so that they could just fit through the waterway.  (Tomas Munita / Associated Press)

A container ship passes through the Miraflores locks Dec. 10, 2004.   (Kathryn Cook / Associated Press)

U.S. President George W. Bush and first lady Laura Bush, right, get a tour of the the Panama Canal from Panama’s President Martin Torrijos and his wife Vivian de Torrijos, as they cross over a walkway at the Miraflores Locks outside Panama City.  (J. Scott Applewhite / Associated Press)

A controlled explosion marks the beginning of the expansion of the Panama Canal project in Paraiso on the outskirts of Panama City in 2007.   (Alejandro Bolivar / EPA)

Cargo ships wait to enter the Pedro Miguel lock in the Panama Canal on August 19, 2008, in Panama City.   (Elmer Martinez / AFP/Getty Images)

A dredger starts work on the main entrance of the Panama Canal at the Pacific coast as a part of an improvement project. The project included the removal of 9.1 million cubic meters of land and rock.  (Alejandro Bolivar / EPA)

Workers on the Panama Canal Authority transfer the first giant gate for the Gatun Locks in July 2014 as part of the canal expansion project.  (Panama Canal Authority / EPA)

The Miraflores Locks at the Panama Canal near Panama City lifts vessels into the Pacific Ocean.  (Rodrigo Arangua / AFP/Getty Images)

A ship is guided by a tug through the Miraflores Locks.   (Rodrigo Arangua / AFP/Getty Images)

A ship is guided by a tugboat through the Miraflores Locks in the Panama Canal.   (Rodrigo Arangua / AFP/Getty Images)

Linehandlers work aboard a ship in the Panama Canal.  (Rodrigo Arangua / AFP/Getty Images)

Construction workers labor in a water tunnel in August 2014 during expansion work on the canal  (Arnulfo Franco / Associated Press)

Cranes tower over the construction site of Panama Canal’s Pacific expansion project on Aug. 8, 2014.   (Arnulfo Franco / Associated Press)