It is exactly half a century since I first entered Ghana. I was twenty-two years old, and I stayed there for over two years, mostly in Nima, a sprawling slum on Accra’s outskirts. My research project was initially political: how would the newly independent country absorb a flood of migrants from the interior as citizens—through party politics, voluntary associations, and public education? Unfortunately, Ghana was then a police state and no one wanted to talk about politics, least of all to me. I rented rooms in Nima and pondered what to do next. I could hardly miss the vitality of the street economy and so I decided to study that instead of politics.

I didn’t classify the bulk of economic activity as “informal” then. Rather, I was impressed by the enterprise of individuals and collected some seventy case studies that became the basis for a doctoral thesis on entrepreneurship. Joining a group of development economists led me to see the problem through their eyes. It was 1970 and the world was turning. Third World cities were filling up fast, but there appeared to be few real jobs for their inhabitants. The specter of mass unemployment, even of revolution, loomed.