In 1847, Congress authorized the secretary of the Navy to contract for additional steamship mail service. One route ran from New York to Charleston, Savannah, New Orleans, and Havana; another from Havana to the Isthmus of Panama, then up the Pacific coast to California and Oregon; and still another—the most important—between New York and Liverpool. By 1853, Congress tried to soothe a South disgruntled by the stimulus to the North’s shipping industry and trade with a steamship line from New Orleans to Tampico and Veracruz in Mexico. . . .
By the time the initial subsidies were halted, in 1859, America’s international mail service was much faster, and its foreign trade had also greatly increased. This growth resumed just after the Civil War, when Congress authorized the postmaster general to contract with steamship owners to transport the mail from the East Coast through various ports to Brazil, and from San Francisco to Japan, China, and Hawaii.