thin Houle of Pike. 1806-1807 Which exploration was first? What was the starting point of the expeditions? Which recent addition to the United States did Lewis and Clark explore? What river did they follow at the beginning? What two general directions did Lewis and Clark travel? Which river did Pike follow in his first exploration? What two general directions did Pike travel in his second exploration? What country claimed the land north of the Louisiana Purchase? What country claimed the land south and west of the Louisiana Purchase? 10. Who claimed the land north and west of the Louisiana Purchase