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. All the members of the credit union, regardless of gender, ethnicity, religious and political beliefs, as well as the size of the monetary share have equal rights. 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. The relationship between credit unions and shareholders arise from the membership and are not customer relationship.