Clearly, the fear of overpopulation is widespread. But the truth is that overpopulation in the United States is not even close to a serious problem. Even globally, overpopulation is an overstated problem. The truth is that the rest of the world has plenty of potential for increased food production: more than enough to feed itself and provide imports for a more populous United States.
To start with just the United States. How many people can the country support? Because I am an agricultural economist by profession, my bias is to first think about food. One simple question is how many people can the United States feed? Well, our net agricultural exports account for about 25 percent of the physical volume of agricultural production, which suggests that if we redirected those exports internally, the US could probably support approximately 25 percent more people. That’s assuming current technology and current diets and current land use. In short, we could feed more than 400 million people, total, merely by consuming locally what we now export.
Consider that the European Union has approximately 300 people per square mile, making it as dense as the ninth-densest US state (that is, similar to Pennsylvania or Florida). The continental United States, on the whole, has about 110 people per square mile (excluding Alaska, an outlier), making the US less than one-third as densely peopled as the EU. Yet the European Union, too, has roughly balanced or even slightly positive agricultural trade. That suggests that Europe, too, has no trouble feeding itself despite being three times as densely settled as the United States.
If the continental United States were as heavily settled as the EU, the US would have nearly a billion people living in it. Granted, the Western US is extremely dry and thus might not support an EU-density population. Nonetheless, if just the states east of the Mississippi had European-style population density, and the other states maintained current population, then the United States would still have more than 400 million people. Achieving European-style densities wouldn’t require technological change. It wouldn’t even require any non-voluntary lifestyle changes or new regulations.
The concern with overpopulation, naturally, often dovetails with concerns about climate change. Won’t higher population devastate the environment? We can’t solve our climate-change problems by having fewer babies. Even if US population stopped growing at around 325 million people in 2017 and flatlined out, it would produce at best a marginal change in global emissions. Plus, accomplishing that trend would require draconian anti-fertility policies and extremely strict immigration laws. Even if US population rises over 500 million people, the impact on the world is barely noticeable. Meanwhile, lowering US carbon intensity by about a third, to around the level of manufacturing-superpower Germany today, has a bigger effect than preventing 100 million Americans from existing.
We should provide the resources for women to take control of their fertility. We should want to reduce undesired conceptions and increase desired conceptions. We should facilitate the kind of human development that tends to reduce desired fertility from the four- to seven-child range to the two- to four-child range as well. But we should do these things because it is to empower individual decision-making, not because we can save the climate through Malthusian reductions.