WASHINGTON -- As the United States declared war against the German empire in 1917 -- signifying the nation's involvement in World War I -- the Department of State identified a need for a secure and reliable way to transport sensitive documents around the world.A year later, the U.S. Army established a wartime courier service, known as the "Silver Greyhounds." Adopting their name from U.K. royal couriers, often referred as "The Queen's Messengers," the Greyhounds could be identified by the greyhound symbol affixed to their uniform.More importantly, the Greyhounds were diven by their motto: "None Swifter than These," as they helped reduce transit times between Paris and Washington from roughly five weeks to less than two.The Greyhound's former motto is still used today by the U.S. Diplomatic Courier Service, who is also celebrating 100 years of dedicated service to the nation. A diplomatic courier is an official of the U.S. government who is appropriately trained and credentialed by the U.S. Secretary of State to accompany classified materials across international borders.Throughout World War I, numerous ad hoc civilian and military couriers were dispatched overseas, but the Silver Greyhounds of 1918-1919 represented the first time in U.S. history that a group of professionals was explicitly organized to safeguard and transport U.S. diplomatic shipments. Following the Armistice of November 1918, the Silver Greyhounds were reorganized into a true diplomatic courier service to support the U.S.-led peace talks that culminated in the Treaty of Versailles.Later In 1985, the Department of State consolidated its separate security activities into the Bureau of Diplomatic Security, and the Diplomatic Courier Service formally became part of the new bureau's "principal element," the Diplomatic Security Service.While yesterday's couriers primarily carried leather briefcases holding files and documents, today's couriers also serve as specialized freight and cargo expediters who daily travel the globe safeguarding our nation's most sensitive shipments.In accordance with the international agreement -- the 1961 Vienna Convention on Diplomatic Relations -- diplomatic pouches carried by credentialed couriers do not go through normal airport baggage-checks and must not be opened, x-rayed, weighed, or otherwise investigated by customs, airline security staff, or other parties.Couriers not only supervise the safe delivery of sensitive and classified documents, but they also manage the security of equipment and construction materials destined for nearly every nation where American diplomats work.More than 100 diplomatic couriers travel the globe, continually troubleshooting and innovating to ensure secure deliveries. In 2017, the Diplomatic Courier Service shipped 116,351 items weighing approximately 5,353,000 pounds.