Millions of American citizens are currently living abroad. However, the United States does not formally count the number of Americans who move to other countries and does not require its citizens to register an official place of residence. This makes keeping track of American expatriates a challenge.
The United Nations Population Division currently estimates that 2,996,223 Americans are living outside the United States, while the U.S. State Department estimates that there are as many as 9 million U.S. citizens living in over 160 countries. Although there is no clear consensus, most estimates show that the numbers are rising.
Some of the most common reasons that U.S. citizens choose to live in other countries involve career opportunities, research positions, and romantic relationships. Other people move overseas because another country offers cheaper health care or a higher standard of living. (A higher standard of living is often associated with a higher gross national income. Here are the 25 richest countries in the world.)