Lewis And Clark's Exploration By ThatOneGirl820 Jan 19, 1803 3rd President, Thomas Jefferson sends a secret letter to congress asking for $2,500 to fund an exploration to the Pacific Ocean. Feb 28, 1803 Congress appropriated the funds for the expedition. May 14, 1804 Meriwether Lewis and William Clark lead a group of explores to explore the US and find a water route to the Pacific. Jan 2, 1805 Lewis and Clark arrived at Great Falls, Montana. Nov 16, 1805 Lewis and Clark arrived at the Pacific Ocean. Mar 24, 1806 Lewis and Clark left Fort Clatsop Winter Camp Sep 24, 1806 Lewis a and Clark returned from their journey