Like the credit cooperatives, credit unions form associations of a higher level, which are called corporate credit unions. The uniqueness of credit unions is that they put together the principles and benefits of financial cooperatives, consumer cooperatives and mutual aid funds, born once by trade unions. Specialization of credit unions to provide financial services to its shareholders requires a particularly strict regulation of membership and acceptable activities. Until the 70's there was a proliferation of the U.S. credit unions due to the increase of their number and the number of shareholders, although it must be acknowledged that there was also and a qualitative growth. Since the early 80's started the process of consolidation of credit unions, leading to a decrease in their number with a simultaneous increase in the total number of members. Over 30% of the assets of credit unions are investments in government securities, certificates of deposit of banks and savings loan associations, as well as in the parent credit unions, and other risk-free investments. Credit unions historically formed as a special form of social support, initially taken upon themselves the social mission of protecting the interests of citizens in the field of financial services. Unlike banks, in order to use the services of a credit union, you have to become its member, having written an application and having paid thus shares and membership fee.