42
application of power to production and transportation,
were the technical requisites for mass production. But
in 1850 little attention was given to power and power
machinery by official sources, and not until I87O were
questions concerning power included among those asked
22
by the Census Bureau. Congress finally provided for
their collection officially in 1879 for inclusion in
the 1880 Census, with good reason. The total horsepower
of all prime movers in the United States more than
tripled in the thirty years after 1850, from 8,495,000
horsepower to 26,314,000 horsepower in 1880. Inanimate
horsepower increased from 2,535000 to 14,734,000 during
that period, and surpassed animate horsepower in about
1870.23
Machine tools round out the picture of technical
changes important to mass production in the United States
after i860.
22
The questions for that year were included
because of interest on the part of the Superintendent of
the Census.
23
Historical Statistics, p. 506, Series S 3-5.
By 1955 the total power of prime movers was
estimated to be 7,272,997 j^30 horsepower, more than 850
times that of 1850, a sizeable increase indeed. Histor
ical Statistics, p. 501.
Power production and consumption have come to be
accepted as one of the best indicators of economic
advancement. Levels of total output correlate highly
with power production. Demands for electric energy in
the United States are expected to double over the next
ten years.