Michigan's banks in the territorial and early statehood years were generally wildcat speculative ventures. More restrained banking activities date from the 1840s when the state's oldest bank, the Detroit Bank and Trust, was founded. A crisis that developed in the early 1930s forced Governor William Comstock to close all banks in February 1933 in order to prevent collapse of the entire banking system. Federal and state authorities supervised a reorganization and reform of the state's banks that has succeeded in preventing any major problems from arising since that time.
There were 180 insured banks in 2002, with assets of $166.9 billion. One hundred thirty-three of those banks were state-chartered. Banks with less than $1 billion in assets ("community banks") account for 82% of the state's insured institutions, but larger banks hold 80% of the state's assets. Community banks in 2002 had relatively high net interest margins (NIMs) (the difference between the lower rates offered to savers and the higher rates charged on loans), largely due to higher loan levels, especially commercial and industrial (C and I) and commercial real estate (CRE) loans.