Principles of cooperative democracy and interaction were adequate to the purposes for which people joined 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. Typically new members of the credit union become citizens having suretyship or recommendations from their friends - members of the credit union. A potential new member of a credit union must submit a recommendation of shareholders in which the referee becomes a warrant of a future member of the credit union. 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. Credit unions are competitors of savings institutions, adding interest on deposits of members. This applies to the shares, as well as to additional funds transferred to the account in the credit union. Contributions from of shareholders in credit unions in no way can be considered as borrowed funds, they come from the shareholders and for the shareholders and can not be used to provide services to third parties. Unlike banks credit unions limit their activities to a closed circle of people.