Preparing for the gargantuan construction work that would be the Panama Canal, Panama's sleepy cities, especially Panama City, which was the capital, and Colon, the second major city, located on the Atlantic side, began to wake to the hubbub of activity as Americans, West Indians, and even Indians, Spaniards, and Greeks began to disembark at the quays along with tractors, cranes, steel, lumber and every conceivable implement one could imagine necessary both to build the largest-ever civil engineering work the world had known and also the complementary works: housing for employees, storehouses, schoolhouses for employees' children, not to mention swimming pools, clubs, and of course, grocery stores. On March 4, 1904, with absolutely no ceremony, U.S. Lieutenant Mark Brooke received from French officials the keys to the French hospitals, marking the official transfer of the French installations to the United States and the beginning of the U.S. construction period.

The construction of the Canal, accomplished between 1904 and 1914, required the removal of gargantuan amounts of dirt and rock, cost the lives of 26,000 men, including those killed during the French construction effort the century before, but resulted in one of the greatest engineering feats of all time. Thousands of vessels have transited the waterway since its construction, carrying everything from coal and steel, iron ore, oil, automobiles, and containerized cargo. Passengers traveling on hundereds of cruise ships per year continue to marvel at its lush surrounding vegetation that contrasts sharply with the nuts and bolts and enormous structures that make possible a rapid, trouble-free transit even after 94 years of service. After World War II and the launching of the U.S. aircraft carrier fleets in the Atlantic and Pacific, the Canal's importance became more commercial than military.