Throughout the 19th century Congress funded expeditions to explore land and sea. In 1836 Congress authorized the United States Exploring Expedition—also called the Wilkes Expedition after its leader, naval officer Charles Wilkes. Its purpose was to circumnavigate the world, promote commerce, and "extend the bounds of science and ... Knowledge." The four-year expedition mapped South Sea islands and Pacific coastlines, established trade, and gathered voluminous information that aided the United States in becoming a leading scientific and naval power.