Cross posted from USxCanada InfoShop
A search for the data that underlies “estimates” of the numbers of U.S. citizens resident outside the United States does not lead far. A total of 6.35 million, excluding military personnel, is one handy number.
A map  provided as part of the information on the web site of American Citizens Abroad (ACA)  appears to be as good a piece of information as any that can be obtained. And even that map data is contradictory (see note following citation).
ACA and Association of Americans Resident Overseas (AARO) pass along figures said to be provided by the U.S. State Department. The only level of detail is for seven regions that cover the entire world. These organizations have been hacking away valiantly for years at this data situation. It seems peculiar that a direct State Department source for this same data cannot easily be found.
Smith  cites older State Department estimates and says that “security concerns” prevent release of more current figures. The Johnson map  likewise contains a note saying that “security concerns” prevent access to any level of detail more fine-grained than the seven large regions.
In reality, “security” concerns seem to equate to embarrassment concerns. The same embarrassment circumstance may also apply to another tarpit of mushy data, the numbers for renunciations of US citizenship. In both cases, lowball might look better for the United States under present policies.
Perhaps the most solid general indicator of numbers is recent ten-year data that indicates “503,585 consular reports of birth abroad (CRBA) were made and passports issued as a result by U.S. embassies between 2000 and 2009” . Factor in births not reported. Consider likely ratios of adults to children. Adjust for possible divergence from norm among adult population. Etc.
There is a history of how the U.S. census has and (mostly) has not dealt with extraterritorial citizens —  and . Any further pursuit of that topic would be a digression from the focus of this short essay.
The ironies of this situation astound. The United States clearly has no good data on citizens who reside outside its boundaries — nor much will to use the U.S. census to develop such data.
Nevertheless, whoever those yet unknown citizens may be, and wherever they may live, the United States seems eager to pursue them, to try to extract resources from them, to give them almost nothing, and to subject them to neverending uncertainties. Especially the ongoing uncertainty that surrounds whatever new measures it may unilaterally decide to unleash on them next.
One unhappy likelihood is that the United States will only deepen the morass that already confronts persons who seek to shed that toxic US citizenship.
In 2012, enjoying liberty translates into declaring independence from the United States?
* * *
 How are we counted? American Citizens Abroad (17 Oct 2011)
 Don L. Johnson. American citizens living aborad [map based on U.S. State Dept. estimates 2011] Association of Americans Resident Overseas (4/08/11)
[Note: Map states total of 6.32 million, yet figures for seven regions add up to 6.35 million]
 Claire M. Smith. These are our numbers: civilian Americans overseas and voter turnout Overseas Vote Foundation (Aug 2010) 13 p.
 Claire M. Smith. Defining the universe: the problem of counting UOCAVA voters Overseas Vote Foundation (May 2009) 8 p.
 Issues of counting Americans overseas in future censuses. U.S. Census Bureau (27 Sept 2001) iii, 17 p.
If we could all, somehow, get together we would be a political force. But… how to?
There is a very good reason why the State Department doesn’t really know. US tax laws.
Nobody knows how many persons with US citizenship are living abroad, because an unknown but undoubtedly significant number of them do not want the US government to know anything about who or where they are, lest the IRS find them and pounce on them. From what I sense this is a problem unique to the US for one simple reason: No other country in the whole world taxes its citizens who are bona-fide residents of another country, It is just that simple. Where citizens of other countries generally try to register with their embassies abroad and keep them posted with address changes, etc. many Americans living abroad do just the opposite; particulary when they are dual citizens. But this is in no way limited to dual citrizens. In my 55 years of traveling abroad I have met several in this category.
This is my opinion on why there is so little concrete data on the size of the American daspora.
The rules for acquiring US citizenship by birth abroad were broadened in the late 1970s, and I wonder if that was entirely wise (especially combined with a requirement that US citizens everywhere in the world file tax returns).
The 2006 Canadian census showed 298,000 people in Canada self-reporting as U.S. citizens. Just over half of those were also Canadian citizens. In other words, if we accept the US embassy’s estimate of a million people in Canada considered US citizens under US law, then more than two-thirds of them don’t acknowledge it, reject it, or (I suspect in many cases) aren’t aware of it.
A very expansive definition of citizenship combined with very rigid, complicated and poorly communicated tax obligations is part of the problem we now find ourselves in.
I find it quite easy to imagine that of six million overseas Americans a minority are willing to acknowledge their citizenship, and many would be astonished that US law considered them to be American.
Broken Man – Elaboration follows on your concluding phrase: many would be astonished that US law considered them to be American.
The 2006 Census shows 298,370 with US place of birth (160,950 Canadian citizens + 137,425 Not Canadian citizens). Of the 160,950 there are 117,425 listed as Canadian citizens only. A different table for Immigrant Population shows a total of 250,535 with US place of birth.
[All of these numbers are based on self-reporting and a 20% sample only.]
A few easy conclusions?
• 117,425 “Canadian citizens only” born in the US [the US may take a different view?]
• 137,425 US citizens lack the protection of Canadian citizenship [CRA will enforce US tax collection]
• 47,835 “non-immigrant” Canadians born in the US
For what it’s worth, the Global Migrant Origins Database (from 2007) lists about 2.2 million U.S. citizens living abroad. (Download their excel file v. 4; the US is in column BD). Mostly this is based on place-of-birth and national immigration department statistics, so it probably misses a lot of dual citizens and people born abroad to U.S. citizen parents.
One amusing factoid from that data: the U.S. immigrant-to-emigrant ratio is about 15-to-1. One of the highest in the world (only Saudi Arabia, Qatar, and UAE are ahead of us — not exactly countries the US wants to emulate, I’m sure). If the U.S. public were more widely aware of this figure they’d probably see it as one more piece of evidence for their “We’re #1!” worldview, but to me it just demonstrates how insular and anti-emigration the homelanders are. Other countries which are also highly attractive as immigration destinations (e.g. most of Europe) have ratios ranging from 1-to-2 up to around 4-to-1). Their people actually get out and see the world.
I calculated all the immigrant-to-emigrant ratios and put them in a Google Docs spreadsheet here for those who are interested:
Well, it certainly seems to be heading in the direction of making it very hard to renounce citizenship. I wonder how far the restrictions will actually go though…I mean, even under Nazi Germany and Stalinist Russia it was still possible to actually renounce citizenship after giving up all of your assets. I don’t see how an absolute ban would get through the US supreme court.
I guess that they could basically reduce the 2 million barrier for the exit tax and just subject everyone to one, or just require a flat 50% percentage of assets to say goodbye.
I take all of these figures about the number of US citizens overseas with a grain of salt. I’ve never registered or spoken with the US embssy, and I believe that I technically left the US incorrectly the last time that I was there by using my “foreign” passport, so they might even think that I am still there. I imagine that several other thousand are probably wrongly counted as still being there as well. I just accept that there are several million who are known, and many more who know but do not want the US to know and lastly many many more with a claim to citizenship, especially through US grandparents.
The US is unwilling to spend money to count expats, and no effort to expand services
The US is trying to extort billions from FFI’s to find our money
Should I conclude that as persons we do not count only our money matters
@usxcanada, The US has made attempts to count US expats living abroad, these attempts have been total failures, so this effort as been totally abandoned.
Why did they fail? I suspect that many US expats go out of their way to not be identified lest the census data be passed on to the IRS which would come after them with a vengeance.
The horror stories of those who came forward voluntariliy to take advantage of Amnesy are legend. US ciizenship- based taxation fills the heart with fear, especially those with “accidental” US citizenship because they were born overseas to one US citizen parent, nationals of other countries who happened by circumstance to have been born in the US but have never lived there, those who were advised by competent authorities that their having become citizens of another country resulted in revocation of their US citizenship (only to find out that as a result of a Supreme Court Ruling their lost US citzenship had been retroactively restored without either their knowledge or consent.)
When I lived in Brazil back in the ’70s when I had gone to the US consulate in Rio de Janeiro for a reason which I don’t remember now, I talked to a young Brazilian, about 30, who had gone there to apply for a business visa to visit the US. The consulate refused to stamp a US visa in his passport because he was born in Maryland when his father was the Brazilian military attache in Washington. As a diplomat his son should not have US citizenship because he was born in the US, but since there was nothing on his Maryland birth certificate that indicated this, the Consul ruled he was a US citizen so he was issued a US passport.
He had returned to Brazil as a baby so this was his first visit to the US since his birth.
He was told nothing about having a US tax obligation when this passport was issued. Back then the State Department and the IRS did not talk to each other, but things are very different today.