Pouring of concrete began at Gatun on August 24, 1909, at Pedro Miguel on September 1, 1909, and at Miraflores in July 1910. Workers completed concreting by September 1, 1913. During the four years of construction nearly 4,500,000 cubic yards were poured at the three lock sites.
The Canal lock system contains 46 miter gates that operate by electric power provided by Gatun Dam. When opened, the gates fit into recesses along the chamber walls, allowing the full utilization of the 110-foot width of the chamber. In 1914, nearly 95 percent of oceangoing vessels were less than 600 feet in length, much shorter than the 1,000-foot-long lock chambers. Engineers installed intermediate gates that allowed the use of 400- or 600-foot lockages, minimizing the amount of fresh water used during a transit.
In 1913, after successfully testing the locks on September 26, Culebra Cut was filled with water. On October 10, the earth dyke at Gamboa was destroyed, joining Gatun Lake with the Culebra Cut and completing the Panama Canal. The S.S. Ancon made the first official transit through the Canal on August 15,1914, though with the outbreak of World War I, the celebration was somewhat subdued.