1950s +1960s: widely-held notion that industrialization would lead to demise of traditional/marginal activities – W. Arthur Lewis’ Nobel Prize-winning essay on structural dualism in labour markets with surplus labour
early 1970s: recognition of persistence of traditional activities – coining of “informal sector” term – Keith Hart study in Ghana + ILO World Employment Mission to Kenya
late 1970s + early 1980s: different theories of the informal sector/economy: dualist, structuralist, legalist, voluntarist