Part geographical location, part time period, and part state of mind, the American West is a concept often invoked but rarely defined. Though popular culture has carved out a short and specific time and place for the region, author and longtime Californian Stephen Aron tracks "the West" from the building of the Cahokia Mounds around 900 AD to the post-World War II migration to California. His Very Short Introduction stretches the chronology, enlarges the geography, and varies the casting, providing a history of the American West that is longer, larger, and more complicated than...