My suggestion would be Legacy of Conquest by Patricia Limerick (1987).

Limerick is one of the leading contemporary scholars on the American West. This book is a solid starting point because it is organizes a chronological story around the contest for property and profit. In this book, the West is viewed as a place of conquest rather than a frontier process. Limerick writes of the competition and different viewpoints of the history of the West, such as the natives, Mormons, Hispanics, Asians, etc. She incorporates anecdotes that tie the past and present West together into an easy-to-read book.