The examination of U.S. crises reveals that the current financial crisis follows past patterns.  An investment bubble creates excess demand for new financing instruments.  During the railroad bubbles of the nineteenth century loans were issued at a pace higher than many companies could pay back. The current housing bubble originated from issuing sub-prime mortgages that assume that housing prices would only rise. The increased demand for credit induces financial innovations and instruments that circumvent existing regulations.  Inevitably, the bubble bursts.The history of financial crises teaches that policy reforms and new regulations cannot prevent future financial crises.