Interactive: Africa to fuel global population growth

By Tyler Fisher and Andrea Fuller, USA TODAY | USATODAY

Today, the United States is the third most-populous country in the world. By mid-century, another nation could take that slot: Nigeria.

That's because the balance of world population is shifting, according to a report released this summer by the Population Division of the United Nations Department of Economic and Social Affairs.

This interactive graphic explores the projected populations of countries through the 21st century. Click a country to learn about its expected population change or animate the map to watch global trends unfold.

Among key changes, according to the U.N.:

African nations are expected to be among the fastest-growing, in large part due to higher fertility rates.

Countries with low fertility, such as European nations, likely will shrink during the coming century. The continent's population could drop 14% by the century's end.

By 2100, the world is expected to have 10.9 billion inhabitants. About 4.2 billion of those are likely to live in Africa.

Though the population in other developed nations may decline, the U.S. is expected to maintain modest growth. That's because of immigration and higher birth rates among immigrants, according to Carl Haub, a senior demographer at the Population Reference Bureau.

The interactive map displays the "medium variant" of the U.N.'s projections, the middle range of a lower and higher set of projections. Click the information button at the bottom of the map for details.