Although Yellowstone is our oldest, most iconic, and most popular national park, it is perhaps, in W. D. Wetherell's words, "America's least-known best-known place." Wetherell, arriving at the park on the eve of his fifty-fifth birthday, feels the need to examine where life's mileage has brought him. In the encounter that follows, a writer entering late middle age confronts not only a magnificent corner of the vast American landscape but also the...