1152 PONTIFICIAE ACADEMIAE SCIENTIARVM SCRIPTA VARIA - 2§

The increases in the two average products were apparently
due to increased purchases of nonfarm products, which were
apparently cheaper than the farm inputs they replaced. While
farm labor increased absolutely over the period, farm labor
declined as a percentage of the total labor force from 49 to 21%.
The United States situation as of 1880 is one that is not
likely to be duplicated in any of the current low income areas
of the world. U.S. per capita income was already at a relatively
 high level (about $400 in 1929 prices) and the income
elasticity of demand for farm products was probably 0.5 or
lower. About a fifth of farm output was exported, thus domestic
 consumption could increase more than domestic output.

TABLE 2

Indexes of Output, Inputs, and Productivity, United States Agri
culture, 1880-1020 (!)

(1847-49 = 100)

Indexes
Farm Output . .
Production Inputs .
Farm Labor .
Farm real estate
All other .
Productivity
Output/labor .
Output/real estate

1880

7

.

+

1890
43
€

27
62

1900
56
72

Ge

1910
61
22

1920 1930
70 72
23 97
Ia% 137
v 96
53 62
75 74
45 48 52
6h 72, 75

M) Source: RarrH A. Loomis and GLEN T. BarToN, Productivity of Agri
culture, United States, 1870-1058. USDA. Tech. Bul. No. 1238 (April.
[961), pp. 57, 38. and 6o-6T

But when per capita incomes are low and the income elasticity
 of demand for food is almost unity, agricultural employment
 must increase absolutely and remain a relatively stable
percentage of total employment unless technological change
occurs.

16] Johnson - pag. 12