514 



Types and Market Classes of Live Stock 



mules produced in the United States are raised in the western and 

 southern sections of the corn belt, and that the center of mule produc- 

 tion is about 300 miles south of the center of horse production. He 

 also states that whereas the number of horses over one year of age on 

 farms in the United States increased only 6 per cent from 1910 to 1920, 

 the number of mules increased 33 per cent, and this rate of increase 

 was almost as great in the North as in the South. ^ It may be added 

 that while horses "not on farms" in the United States declined 46 per 

 cent from 1910 to 1920, mules "not on farms" increased 28 per cent. 



Assuming that the average life of mules is about 15 years, there 

 will be a loss each year of 1 out of every 13 mules two years old or over. 

 Replacements are made from the mule foals raised each year. States 



Fig. 203.— Distribution of mules two years old or over in the United States. 



which have 1 mule foal on January 1 to every 13 mules two years old 

 or over (a ratio of 1:13) probably produce sufficient foals to maintain 

 their present number of mules. ^ States which produce less than this 

 proportion of mule foals must buy from other states in order to replace 

 losses among working mules. States which produce more than this 

 proportion will have a surplus for sale. Note the ratios in the follow- 

 ing table of leading mule-using states, based on census returns: 



lA Graphic Summary of American Agriculture, U. S. Dept. Agr. Yearbook, 

 1921, pp. 471,473. 



2Xhe census of 1920 reports a ratio of 1:12 for the country as a whole, and this 

 provides an increase in the number of mules in the United States. 



