Once the Panamanian victory was secured, with American support, construction on the canal began in May 1904. For the first year of operations, the United States worked primarily to build adequate housing, cafeterias, warehouses, machine shops, and other elements of infrastructure that previous French efforts had failed to consider. Most importantly, the introduction of fumigation systems and mosquito nets following Dr. Walter Reed’s discovery of the role of mosquitoes in the spread of malaria and yellow fever reduced the death rate and restored the fledgling morale among workers and American-born supervisors. At the same time, a new wave of American engineers planned for the construction of the canal. Even though they decided to build a lock-system rather than a sea-level canal, workers still had to excavate over 170 million cubic yards of earth with the use of over one hundred new rail-mounted steam shovels. Excited by the work, Roosevelt became the first sitting U.S. president to conduct an official international trip. He traveled to Panama where he visited the construction site, taking a turn at the steam shovel and removing dirt. The canal opened in 1914, permanently changing world trade and military defense patterns.