An 8,000-mile, 28-month mission into the unknown was more of an odyssey than a trip. The western U.S. was almost completely a mystery and had, the year before, just doubled in size. The Corps of Discovery co-leaders Meriwether Lewis and William Clark were the right people at the right time. The pair were friends, and they complemented each other in personality traits and in their respective skills. The mission succeeded in great part because of this synergy. Intelligent, curious, and well-read, Meriwether Lewis was a strong, strategic leader, in spite of a moody temperament and bouts of depression. He was President Thomas Jefferson's handpicked choice to head up the expedition. He was the botanist, naturalist, and faithful cataloguer of the trip. In contrast, Clark was a practical man and a problem solver. His steady, easygoing temperament balanced Lewis' mercurial nature. Blessed with an innate sense of orientation and landscape, he was an excellent cartographer, and even today historians marvel at the accuracy of his work.