From 2018 to 2019, the population in the US expanded at .48% or about 1.5 million people, with a total population outstanding of around 328 million. 

The report mentions how a lack of migrants entering the country along with a decline in natural increase has led to waning population growth since the 2008 financial crisis. 

William Frey, a senior fellow at The Brookings Institution, told AP that the 2019 population growth is the slowest since 1917/18.

"With the aging of the population, as the Baby Boomers move into their 70s and 80s, there are going to be higher numbers of deaths," Frey said. "That means proportionately fewer women of childbearing age, so even if they have children, it's still going to be less."

The Census Bureau said the natural population increased by 957,000 from 2018 to 2019, which is the first time it has breached 1 million since the late 1970s.

Immigration has also been on the decline since adding 1 million in 2016. From 2018 to 2019, immigration inflow only added 595,000 to the total population.