<P> Economists and historians disagree as to what role the crash played in subsequent economic, social, and political events . The Economist argued in a 1998 article that the Depression did not start with the stock market crash, nor was it clear at the time of the crash that a depression was starting . They asked, "Can a very serious Stock Exchange collapse produce a serious setback to industry when industrial production is for the most part in a healthy and balanced condition?" They argued that there must be some setback, but there was not yet sufficient evidence to prove that it will be long or that it need go to the length of producing a general industrial depression . </P> <P> But The Economist also cautioned that some bank failures were also to be expected and some banks may not have any reserves left for financing commercial and industrial enterprises . They concluded that the position of the banks is the key to the situation, but what was going to happen could not have been foreseen . </P> <P> Academics see the Wall Street Crash of 1929 as part of a historical process that was a part of the new theories of boom and bust . According to economists such as Joseph Schumpeter, Nikolai Kondratiev and Charles E. Mitchell, the crash was merely a historical event in the continuing process known as economic cycles . The impact of the crash was merely to increase the speed at which the cycle proceeded to its next level . </P> <P> Milton Friedman's A Monetary History of the United States, co-written with Anna Schwartz, advances the argument that what made the "great contraction" so severe was not the downturn in the business cycle, protectionism, or the 1929 stock market crash in themselves--but instead, according to Friedman and Schwartz, what plunged the country into a deep depression was the collapse of the banking system during three waves of panics over the 1930--33 period . </P>

What caused the stock market crash in the great depression