Like the credit cooperatives, credit unions form associations of a higher level, which are called corporate credit unions. Specialization of credit unions to provide financial services to its shareholders requires a particularly strict regulation of membership and acceptable activities. National Credit Union Insurance Fund was created by Congress in 1970 to insure deposits of credit union members in the amount of 100 thousand dollars. Credit unions appeared in England in the 19th century. In 1844 a group of workers from Rochdale established the first cooperative. Credit unions base their activities on savings of shareholders, their shares and savings contributions, which make up the fund of mutual financial assistance - a source of cash loans to shareholders.