The United States Exploring Expedition of 1838–1842 was an exploring and surveying expedition of the Pacific Ocean and surrounding lands conducted by the United States. The original appointed commanding officer was Commodore Thomas ap Catesby Jones. Funding for the original expedition was requested by President John Quincy Adams in 1828; however, Congress would not implement funding until eight years later. In May 1836, the oceanic exploration voyage was finally authorized by Congress and created by President Andrew Jackson.
The expedition is sometimes called the U.S. Ex. Ex. for short, or the Wilkes Expedition in honor of its next appointed commanding officer, United States Navy Lieutenant Charles Wilkes.