How many people live in the Lagos metropolitan area?

How to get close to this number

Work from the country. Nigeria has over two hundred million people and this is its largest city by a wide margin, holding somewhere under a tenth of the national population in one metropolitan area. That fraction of that population gives a figure in the mid-teens of millions.

The growth rate in the explanation is what makes this city significant rather than the current total: an estimated two thousand additional residents every day. That is a city adding the population of a small town every fortnight, sustained for decades, and no infrastructure programme can be built fast enough to keep pace with it.

The projection is the part worth sitting with: potentially past thirty million by mid-century, which would put it among the largest cities on Earth. Most of the urban growth remaining in this century is happening in cities that Western readers could not name, and this is the largest example of it — the list of the world's biggest cities in 2050 looks nothing like the list today.