By TheStreet What Was the Great Depression? When Did It Happen?The longestrecession in American history took place between 1929 and 1939. Known as the Great Depression, this economic crisis was noteworthy in terms of both its length and its severity. There had never been anything like it before, and hopefully, there never will be again. Stretching more than a decade, the Great Depression began with astock market crash. On Black Monday—October 29, 1929—over 16 million shares were sold in a wave of mass capitulation over the course of a single trading session, bankrupting thousands of investors …