Frankly, I don't understand why everyone likes this book. It dedicates entirely too much space to trees that grow primarily in the east, south east, and Mexico(the author considers central Texas as "western," so any trees that touch this area from the east is included). Yes, it does have good information on many western trees and you will likely find the tree you're looking for, but if he would have stuck to, say, Montana, Wyoming, Colorado, New Mexico and west he could have gotten more information and more photos (nearly 300 of the 400 trees in this book have no photo) in the same size book or smaller.
As a backpacker, weight is an important factor to consider when deciding whether something is worth carrying or not. Carrying this book is like throwing an extra one pound lead weight in my pack. There is at least that much information in this book that is useless to me living in Washington State. As much as I would like to take this book for the info it does have, I just can't afford to pack that much extra useless weight, and then only to be frustrated to not find a particular tree I want to identify because there's no photo (it has happened). Again, if he would have stuck to western trees only, there would no doubt be more and better information and photos of all the trees that grow predominantly in the west in the same size book.
Peterson Field Guides seem to be primarily focused on the eastern half of the United States (I understand they're outstanding for that region) and it seems they haven't strayed too far from the eastern states with this book either.
