Page:Graphic methods for presenting facts (1914).djvu/238

 Abstract of the Thirteenth Census of the United States, 1910

Fig. 179. Average Value of Land in Farms in the United States per Acre by Counties in 1910

In Fig. 178 the shading represented unit quantities. Here it represents unit values. Maps of this nature are also of great assistance in studying the chief characteristics of cities and suburbs as regards land values, population density, etc.