Corporate credit unions are united on a cooperative basis in the Central Credit Union (US Central Credit Union). Most modern credit unions represent specialized consumer cooperatives of citizens associated by the principle of social community: place of work, place of residence, profession, or any other shared interest. The relationship between credit unions and shareholders arise from the membership and are not customer relationship. Credit unions, like today's credit unions, emerged in the 19th century in Germany as a result of crop failure and famine.