REVIEWS 179 



tract of worthless land. Miss Semple maintains that because of the 

 great strategic importance of the Gila River depression as a passway to 

 the coast, money was never better spent. 



Miss Semple believes the most potent factor in American expansion 

 to have been the abundance of free land. The exhaustion of the sup- 

 ply has led to a recent exodus of westerners into Canada, over 50,000 

 going in the three years following 1899. It is pointed out that we 

 must look to the recently initiated national system of irrigation in the 

 arid West for the checking of this migration. 



The arrangement of the matter in the book is not always the best, 

 and a very few important topics are slighted. For instance, the dis- 

 covery of gold in California does not receive due emphasis as a factor 

 in American expansion. Such shortcomings are few, however, and the 

 book is to be heartily commended to all students of geography and 

 history. 



H. H. B. 



