[Oberon]

If a couple doesn't have two children in their lifetimes to replace themselves, plus a few percentage points extra to make up for the kids that die early and the people who never marry, the net effect is to shrink the population.

Of course, this is without accounting for immigration. The numbers you cite probably included immigration in their reckoning.

[ivyleaguebrat]

According to the CIA World Facbook, as of 2009 the fertility rate was 2.05 births per woman. As Oberon indicated, people commonly cite 2.1 as the replacement rate. And the rate is trending down.

However, the population is still growing—by about 1% per year—probably mostly due to immigration.

https://www.cia.gov/library/publications/the-world-factbook/geos/us.html