22 



Yearhooh of the Department of Agricultm'e, 1921. 



Fig. 15. — This map is based largely upon drainage reports available in the OflSce of 

 Irrigation and Drainage Investigations, and upon soil survey, topographic, and Land 

 Office maps. These reports and maps were compared with statistics of drainage enter- 

 prises and of land in farms needing drainage, available for the first time in the 1920 

 census, by L. A. .Tones, of the Bureau of Public Roads, and F. .T. Marschner, of the 

 Office of Farm Management and Farm Economics, who drew the map. Two-thirds of the 

 land unfit for cultivation without drainage is in the Southern States, and one-half 

 of the remainder is in the three Lake States. Nearlv all of the wet land in the South, 

 except the Florida Everglades and prairies, tidal marsh, and Giilf coastal prairies, is 

 forested, and requires both drainage and clearing ; but much of the wet land in the Lake 

 States consists of unforested peat bogs. 



