If Johannesburg were a country, it would be the third-richest state in Africa on a per-capita basis, and it would be the richest on the mainland of Africa.

This is according to an analysis done by The Common Sense.

Johannesburg, as an entity, has a GDP of between $60 billion and $65 billion (equivalent to about 15% of South Africa’s overall economic output). Comparing Johannesburg’s total economic output to other countries in Africa (and excluding South Africa) would make Johannesburg the 13th-biggest economy in Africa. Ahead of it would be Egypt, Nigeria, Algeria, Morocco, Angola, Kenya, Ghana, Ethiopia, Côte d’Ivoire, Tanzania, and Uganda, with Johannesburg’s economy being slightly bigger than those of Cameroon, Tunisia, and Zimbabwe.

However, in terms of population, Johannesburg is much further down this list. If it were its own country, its population of roughly 6.5 million, according to the latest estimates, would place it 37th in Africa, with a population roughly equal to Libya, and slightly more than Liberia.

But it’s on per-capita income where our hypothetical Johannesburg city-state really shines. It would have a per-capita income of around $10 000, making it the third-richest country in Africa, behind only the small island nations of Mauritius and the Seychelles, and higher than Gabon, Botswana, and Equatorial Guinea. Residents of our Johannesburg city-state would also be about 50% richer than the average South African.

Cities around the world are significant generators of wealth and should be treated as important national assets by governments. As renowned Harvard economist Ed Glaeser has argued, cities are one of humanity's greatest inventions. And it is not because of the buildings or infrastructure you find in the city, but because they are places where human beings come together and share ideas, collaborate, and innovate.

One of the most important projects of the government should be to make sure that South Africa’s great cities, such as Johannesburg, function well and are places where people want to work and move to. It is not an exaggeration to say that if Johannesburg succeeds, so will South Africa.