t GEOGRAPHICAL CONCENTRATION. 



within sight of the Rocky Mountains. 



In the case of wheat the area of principal production has 

 undergone great changes during the last half-century. While 

 its center moved steadily westward for forty years, as was 

 the case also with that of the production of corn, oats, and 

 Parley, the result of that remarkable redistribution of the 

 productive area which occurred during the closing years of 

 the decade ending with 1889 was that the two states of prin- 

 cipal production were as widely separated geographically as 

 they are in their physical conditions, Minnesota leading with 

 11.17 percent of the total and California standing second 

 with 8. 73 per cent, while the addition of the crops of Illinois 

 and Indiana raised the proportion to 35. 85 per cent. Although 

 this is a smaller percentage of the total crop of the country 

 than was contributed by the four leading wheat-producing 

 states at any previous agricultural census, it is a significant 

 fact that more than one-third of the total production of the 

 principal bread-plant had to be credited to so limited an area. 

 But whatever the changes in the location of the wheat-pro- 

 ducing area there has always been a more or less marked 

 geographical concentration. In 1839 61.52 per cent of the 

 total wheat crop was produced in four states, containing only 

 5.84 per cent of the entire land surface of the country. In 

 1889 those same states produced only 15.66 per cent of the 

 total, while four others, containing 11.01 per cent of the 

 entire land surface, produced 35.85 per cent of the total 

 crop. 



The cultivation of oats was centralized to so great an ex- 

 tent in 1839 that 56.20 per cent of the total oat crop of the 

 country was the production of four states. Succeeding de- 

 cennial censuses have found various changes in the area of 

 principal production, until the states that formerly stood at 

 the head of the list have come to make relatively small con- 



