A comparison of these two maps shows at a glance the sections in which the greatest

growth of population had taken place in a period of 110 years.

2. In view of the 1920 map, see 179A.

182i

GRAPHIC PRESENTATION

5^

\5< Bev

National Association of Motor Bus Operators, Washington, D. C, "Bus Facts for 1938."

A. Rafes of Gasoline Tax Per Gallon in the Various States as of January I, 1938.

Compare this method of presenting gasoline tax information with the method used in 195A.

WPA, Division of Social Research,

Dollors CD Less Ihon20 ^20-30 ■130-40 40 ond more

'Landlord and Tenant on the Cotton Plantation," 1936.

Per Capita Amount of Obligation Incurred by Each of the States for Ennergency Relief for Thirty-three Months -- January 1933 to Septennber 1935.

The appearance of this map indicates that it was made on a "mechanical" intensity shading map, a device developed by the graphics section of the Works Progress Administration. "State pieces" of the desired shading are placed in "state compartments" of an aluminum base map of the United States. These state pieces are interchangeable, and there are six sets of shadings from which to choose.

The time required to prepare such a density map, photographing included, is about one hour, compared with eight hours if the shading had been done by a draftsman.

CROSSHATCHED AND COLORED MAPS

N Y New York Hrrald Tribune, September 20, 1938.

A. Racial Minorities in Western Czechoslovakia in 1938.

SCALE .7

The variety of shadings given in this map is particularly interesting, as well as the arrangement of the legend.