Calls for high speed rail would be at least an order of magnitude louder and more expansive if Matt Yglesias’ plan to increase the United States’ population to one billion becomes reality. This proposal is based on transit expert Alon Levy’s plan for high speed rail in the eastern US.
With so many large cities, high speed rail lines would blanket the eastern half of the country and the southwest, and even expand into Appalachia and the Rockies. Sets of megacities like the Acela corridor and New York/Chicago would justify even faster lines for additional capacity, just as Japan is building a maglev train to increase speed and add capacity between Tokyo, Nagoya, and later Osaka.
MSAs shown based on population; Rail Lines shown based on prioritization and track speed
City populations were estimated by first scaling existing metropolitan statistical area (MSA) populations proportionately, with 89% of the estimated population inside MSA boundaries as compared to 86% today. Then, populations were weighted toward bigger cities based on their higher agglomeration effects but slightly less to the largest cities because of higher congestion effects. Finally, cities with lower and negative growth rates in the past decade were weighted higher based on One Billion Americans’ plan to increase immigrant settling, and therefore investment, in those cities.
The estimates show New York would grow from 19 million to 63 million people, Los Angeles from 13 to 48 million, and Chicago 9 to 38 million. There would be 8 cities with populations over 20 million and 19 total megacities over 10 million. There would be 150 cities over 1 million, as compared to 53 today. The MSAs estimated to be home to over 20 million people are listed:
| MSA | Population at OBA | Population in 2019 | % Change 2010-2019 |
| New York City, NY | 63,368,960 | 19,216,182 | 1.69% |
| Los Angeles, CA | 47,903,217 | 13,214,799 | 3.01% |
| Chicago, IL | 37,811,208 | 9,458,539 | -0.03% |
| Philadelphia, PA | 23,458,758 | 6,102,434 | 2.30% |
| Dallas, TX | 22,107,108 | 7,573,136 | 18.95% |
| Washington, DC | 20,653,113 | 6,280,487 | 11.17% |
| Houston, TX | 20,516,253 | 7,066,141 | 19.35% |
| Miami, FL | 20,388,376 | 6,166,488 | 10.82% |