<P> Another effect of rapid technological change was that after 1910 the rate of capital investment slowed, primarily due to reduced investment in business structures . </P> <P> The depression led to additional large numbers of plant closings . </P> <P> It cannot be emphasized too strongly that the (productivity, output and employment) trends we are describing are long - time trends and were thoroughly evident prior to 1929 . These trends are in nowise the result of the present depression, nor are they the result of the World War . On the contrary, the present depression is a collapse resulting from these long - term trends .--M. King Hubbert </P> <P> In the book Mechanization in Industry, whose publication was sponsored by the National Bureau of Economic Research, Jerome (1934) noted that whether mechanization tends to increase output or displace labor depends on the elasticity of demand for the product . In addition, reduced costs of production were not always passed on to consumers . It was further noted that agriculture was adversely affected by the reduced need for animal feed as horses and mules were displaced by inanimate sources of power following WW I. As a related point, Jerome also notes that the term "technological unemployment" was being used to describe the labor situation during the depression . </P>

What was the trigger of the great depression