Today, 3.9 billion of us live in cities. That’s more than half the world’s population. By 2050, two-thirds of us will live in urban areas.

Today is World Population Day, and this week the United Nations Population Division released the latest version of its World Urbanization Prospects. The 2014 projections show continued population growth and an additional 2.5 billion city-dwellers by 2050—with almost 90 percent of them in Asia and Africa. But while numbers tell a compelling story, it is crucial to ensure that the urban poor do not get lost in the aggregate.