Comment by tombrossman

Strange that someone down-voted you, as this is a fair question.

> Curious how you found this number, have a source?

I don't have the source handy but have seen the estimated 10 million figure cited repeatedly. But maybe it is about a million too high, as the US Department of State estimates nine million in this 2020 publication: https://travel.state.gov/content/dam/travel/CA-By-the-Number...

This Wikipedia page has a lot more info for those interested: https://en.wikipedia.org/wiki/Emigration_from_the_United_Sta...

Using FVAP stats to me seems problematic, because just like the general population, many US citizens do not bother registering to vote (though they do acknowledge this on the page you linked to and try to control for it).

State likely have a more accurate estimate from knowing how many passport renewals originate from overseas addresses. I am sure some Americans renew or replace their passports while merely travelling overseas, but I cannot imagine this is a routine practice.