Lewis and Clark in Kentucky- Cumberland Gap. Meriwether Lewis, coleader of the Lewis & Clark Expedition, with a party of Expedition veterans and a Mandan Indian delegation, went through Cumberland Gap in Nov. 1806 en route to Washington to report on the expedition. Over. (Reverse) Expedition coleader William Clark traveled through the Gap in Dec. 1806 on his way to Washington to reunite with Lewis and to report to President Thomas Jefferson and other government officials about the journey.