HONG KONG — With the U.S. presidential race a dead heat in the last days before the election, Democrats and Republicans are seeking votes not just in every corner of the United States but also around the world.

The Federal Voting Assistance Program (FVAP) estimates there are almost 3 million eligible American voters living outside the U.S., including tens of thousands of U.S. service members and their families.

Voter turnout among this group is low — less than 8% in the 2020 presidential…