The fertility rate measures the average number of children a woman in a specific area will have over the course of her lifetime.

In fact, 2.1 is a key threshold. At this level, the area’s population remains self-sustaining Above it, populations grow. Below it, populations decline.

As seen from the map, most of the Americas, including its largest countries, the U.S., Brazil, Canada, and Mexico, are all below the 2.1 threshold.

• More than half of American households have no children
• The U.S. hits a record low fertility rate. Is that good or bad?