Imagine being asked by the president of the United States to explore an unknown part of the country. That's exactly how Lewis and Clark found themselves blazing a trail west from Missouri to the Pacific Ocean. Along the way, they met American Indian tribes and documented plants and animals they had never seen before. Lively language, historical illustrations, and primary source journal entries from the explorers help readers feel as if they were a part of the journey. Meets Common Core critical thinking standards, and provides strong ties to social studies standards on westward expansion.