BMO Harris Bank, N.A. is an American bank based in Chicago, Illinois. It is a member of the Federal Reserve System and operates branches in the states of Illinois, Indiana, Arizona, Missouri, Minnesota, Kansas, Florida, Wisconsin, and California. BMO Harris Bank has over 600 branches and 1,300 ATMs and employs 14,500 staff in the United States. BMO Harris Bank is the twenty-first largest banking institution in the United States.