Book excerpt: In 1803, President Thomas Jefferson authorized the purchase of the Louisiana Territory, a vast land that doubled the size of the United States. Jefferson soon appointed Meriwether Lewis and William Clark to explore the western territory and find a route to the Pacific Ocean. The adventures of this expedition are some of the most exciting of American history. Both of these chapters of western expansion in the United States, important components of the social studies curriculum, are illuminated in this engaging volume, full of helpful maps, vibrant images, and fascinating historical facts.