Drive through a few underpopulated towns and tell me that there's no place for more people in America. Empty downtowns, empty houses, empty factories... There might be economic reasons why people don't want to or can't live in these places, but the one thing we absolutely have enough of in this country is space.
Fun fact, Appalachian has some of the world's oldest mountains, older than the atlantic ocean, the Scottish Highlands are part of the Appalachian range.
After reading through the comments it could also be related to climate change but what first came to mind was the american housing crisis. Some people seem to think that the housing crisis could be solved by having more room for houses while, how I understand it, it is actually not a problem of available living space but a problem of affordable living space.
A simple map of population density across the US should clearly show that lebensraum is not the problem indeed. It's more a question of places that are both desirable for the opportunities they offer, while being affordable.
Hold on y’all, we -justyoulistenhere- get a buncha bulldozers and push thems dirt into the water, just like Ja-apan did right? And get this! Then there’s MORE AMERICA!