There are only 160 million US passports in circulation (out of a population of 330 million. So roughly half. Of course HN people tend to be middle class or higher so they'd more likely be in that 50%. But still, the US is huge (roughly the size of Europe (Europe is approximately 10,180,000 sq km, while United States is approximately 9,833,517 sq km). There's plenty of places to go in the US without needing to go elsewhere. And look at the tiny passport numbers in the 1990s! That's because before 9/11 you didn't need one to go to Canada or Mexico if you had other identification (like a driver's license) showing you were from the US. I've heard that you can still go to Canada that way if you drive rather than fly, but I haven't tried it.

https://travel.state.gov/content/travel/en/about-us/reports-...