"The Case for Open Borders": Not a rush

World map. Image source.

Here's another quote from "The Case for Open Borders". This section is talking about the worry that opening the border will cause a huge dramatic rush of migrants to come. From page 194:

7. Open Borders Doesn't Mean a Rush to Migrate

Across the globe, about 14 percent of the global population-- around seven hundred million people-- would, according to recent Gallup polls, like to migrate. Financial burdens, family ties, and fear of the unknown, however, keep a lot of them at home. Plus, many of those potential migrants wouldn't migrate in the same direction. Despite the lure of the Hollywood-baked American dream and economic and political pressures in "sending countries," most people want to stay at home.

Puerto Ricans have enjoyed the unimpeded right to migrate to the far wealthier mainland United States since 1904, but they haven't left the island empty. Similarly, Eastern European countries added to the EU free-migration zone did not swarm Western European countries with their citizens. Absent lethal climactic or political threats, most people tend to want to stay where they are.