“There are two main ways that the US could increase overall population growth: by encouraging people to have more children or by increasing immigration levels.
On their own, pro-natalist policies have historically failed to increase birthrates in the kinds of numbers that would be required to stave off stagnant population growth. Internationally, research has shown that child allowances have led to slight, short-lived bumps in birthrates. From 2007 to 2010, Spain had a child allowance that led to a temporary 3 percent increase in birthrates, but that was mostly because more people decided to have children earlier, rather than have more of them. After the allowance was revoked, the birthrate decreased 6 percent.”
“Immigration is a much more reliable driver of population growth. The average age of newly arriving immigrants is 31, which is more than seven years younger than the median American, meaning that they could help replace an aging workforce. They are also more entrepreneurial, which encourages economic dynamism, and more likely to work in essential industries, such as health care, transportation, construction, agriculture, and food processing.
Immigrants may also help stave off regional population declines. Immigrants are more likely to settle in areas where foreign-born populations already live, which are typically large metro areas that have lost population in recent years. Frey found in a 2019 report that, of the 91 large metro areas that gained population since the beginning of the decade, 15 would have actually lost population were it not for immigration, including New York, Chicago, Detroit, and Philadelphia. In another 11 large metro areas, immigration accounted for more than half of their population growth.
Refugees are also more likely to settle in less dense population centers where housing costs are lower, possibly reinvigorating the nearly 35 percent of rural counties in the US that have experienced significant population loss in recent decades.
Raising immigration levels wouldn’t necessarily require a major reimagining of the US immigration system, though that might offer more flexibility to reevaluate immigration levels periodically — it could be accomplished by just increasing the caps on existing forms of visas and green cards.”