Credit unions encourage savings of citizens, setting compensation payments (interest) on savings and provide from these savings loans to their members. The number of shareholders of a credit union is limited and formalized by a list. Limit of the number is defined by the assembly and such assembly establishes the charter. Among the U.S. credit unions, there are three groups that differ in terms of assets, shareholders, and business services. Share contributions are transferred to the credit union on the basis of membership for the whole stay of a shareholder as member of the credit union and are the basis of membership. 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. In some cases, the initiators of credit unions can be trade unions, associations such as social support centers and others.