The Co-operative Group formed gradually over 140 years from the merger of many independent retail societies, and their wholesale societies and federations. In 1863, twenty years after the Rochdale Pioneers opened their co-operative, the North of England Co-operative Society was launched by 300 individual co-ops across Yorkshire and Lancashire. By 1872, it had become known as the Co-operative Wholesale Society (CWS). Through the 20th century, smaller societies merged with CWS, such as the Scottish Co-operative Wholesale Society (1973) and the South Suburban Co-operative Society (1984).