Open Borders

I caught wind of Open Borders: The Science and Ethics of Immigration by Caplan and Weinersmith via Tyler Cowen's Marginal Revolution blog.

A detailed critique is well beyond my abilities. However, one passage from page 8 of the preview currently available on Amazon lists this Q&A:

"The country is full. We no longer have room for mass immigration"

"There's ample room left. If the continental U.S. were as packed as a low-density city like Los Angeles, everyone on earth would fit."

Going to the notes on p. 217:

"According to the last Census (United States Census Bureau 2018a), Los Angeles County has a population density of 2,419 people per square miles. Since the continental United States is 3,119,885 square miles in area, this are would contain about 7.6 billion people, the current world population."

This is a horrifying simplification of a massively complex question and it has been bothering me for quite a while. The idea that the entire landmass of the U.S. is capable of development at any density is absurd. The constraints on long-term inhabitation of any place are far more complex. This is either a straw-man argument or a significant blind-spot in the authors' understanding. I'll give them the benefit of the doubt and guess that it is a lack of knowledge about development and environmental economics. This seems to imply that you can be a successful economist and know very little about the natural world upon which all economic activities depend.

I'm also not an expert in those fields, but I'm at least somewhat aware of them. At higher densities than Los Angeles County, we could certainly accommodate many more people physically that we do now. Assuming everything else can be addressed with technology and design, can we provide those people with clean water indefinitely?

http://css.umich.edu/factsheets/us-water-supply-and-distribution-factsheet

Doing some freewheeling estimates, we would have to cut per capita consumption to below 100 gallons, a rate that appears to be well below anywhere in the developed world. So maybe, but it would be incredibly difficult.

http://chartsbin.com/view/1455

We've long had essentially open borders for pollution and for the transfer of water via grain sales and other water-intensive industrial processes. How much of the developed world's current wealth is dependent on those externalities?