Estimates of the number of Americans living outside the United States are very rough and quite varied. Heitor David Pinto delved into the complex way in which one would define and an American (see note below). He does not take into account how many in his estimate may be spending part time abroad and part time in the United States. Overall, he estimates that there are about 5.5 million U.S. citizens who are living outside the country. 1.2 million citizens per his estimate live in Mexico and one million live in Canada. About 300,000 live in the United Kingdom. 280,000 live in Isreal, the equivalent to about 3% of the non-Arab population of Isreal.
Note that the organization promoting Pinto’s estimate, the Associations of Americans Resident Overseas, is most likely to favor a high estimate
How Pinto came to his estimate
The United Nations estimates that about 3 million American live outside the U.S. (go here).
Pinto started from data compiled by the United Nations for 2020 from the most recent census of every country, and updated it with U.S. census data for 2022 and with census data for the years 2010 – 2023 from some individual countries. The census data of each country shows the number of people residing there who were born in each other country so, in the case of Americans abroad, it means only people born in the U.S. Pinto then took the more detailed census data from some countries showing parents’ place of birth to estimate the number of Americans born there from a parent who was born in the U.S., and applied it to all other countries proportionally.
His analysis presents the number of U.S. citizens living abroad as people born in the U.S. plus those born abroad with at least a parent who was born in the U.S. (so it includes the so-called “accidental Americans”). He also included naturalized citizens, assuming that they have the same emigration rate from the U.S. as the rest of the U.S. population. This analysis is an admitted simplification, as it includes some people who are not U.S. citizens (those born in the U.S. from foreign diplomats, or born abroad from American parents who didn’t reside in the U.S. for enough years to transmit U.S. citizenship, or those who renounced U.S. citizenship). But there is no data available to estimate these particular cases and their numbers are thought to be relatively small. Mr. Pinto’s estimate does not include military personnel or their families.