The banking system of the United States had on the eve of the crisis of 2007 the following main characteristics:

funding market largely predominates over the financing of the economy by the credit. This does not mean that household debt has become one of the highest in the world;
multiple banks, with nearly 7,200 commercial banks and local banks still very numerous;
few large universal banks ranked among the top global banks (Citigroup, Bank of America, JP Morgan Chase …)
very large specialized banks, including five investment banks Goldman Sachs, Lehman Brothers, Bear Stearns, Morgan Stanley and Merrill Lynch;
system control and monitoring highly fragmented, the Central Bank of the United States (Federal Reserve System – FED) include not having authority over investment banks specialized.

This is a very specific history largely explains these structures.

Control by the Federated States

The System of Banks in USA is very original because it is characterized by two distinct types of banks: banks controlled by the federal government and banks supervised by the states. This duality is the result of the construction of the U.S. banking system. At the end of the eighteenth century, the question arose whether it was the federal government to grant bank charters or states. Faced with fears of too much centralized power, many representatives of farmers and other groups have advocated for the allocation of bank charters by states. Thus until 1863, commercial banks were supervised by the Banking Commission of the State in which they exercised. But this system has led to many abuses, since the issue of money was not controlled and bank failures were numerous.
The control and protection by the Federal Government

The creation of federally chartered national banks was made possible from 1863, but did not prevent periodic banking crises including the particularly serious in 1907. Following this, a central bank which all commercial banks like banks in Dallas  must be members of the country (the Federal Reserve System) was created in 1913. Its action does not prevent the Great Depression following the stock market crash of 1929. Thousands of banks failed and thus ruined the economies of the depositors of commercial banks. To ensure depositors and to prevent these failures, the Federal Deposit Insurance Corporation (FDIC) was created in 1933. It works on the mechanism of insurance: commercial banks have to pay an insurance premium to the FDIC for depositors.