Voters cast ballots in great numbers in a year when there is an election for what?

If early voting trends are any indication, a record number of Americans could vote in the 2020 presidential election. As of this writing, more than 100 million early votes have been cast by mail or in person – more than two-thirds of the total number of votes cast in 2016.

We won’t have anything like a definitive assessment of 2020 turnout rates for some time after Nov. 3. But in the 2016 presidential election, nearly 56% of the U.S. voting-age population cast a ballot. That represented a slight uptick from 2012 but was lower than in the record year of 2008, when turnout topped 58% of the voting-age population.

So how does voter turnout in the United States compare with turnout in other countries? That depends very much on which country you’re looking at and which measuring stick you use.

Political scientists often define turnout as votes cast divided by the number of eligible voters. But because eligible-voter estimates are not readily available for many countries, we’re basing our cross-national turnout comparisons on estimates of voting-age population (or VAP), which are more readily available, as well as on registered voters. (Read “How we did this” for details.)

How we did this

Overall, 245.5 million Americans were ages 18 and older in November 2016, about 157.6 million of whom reported being registered to vote, according to Census Bureau estimates. Just over 137.5 million people told the census they voted that year, somewhat higher than the actual number of votes tallied – nearly 136.8 million, according to figures compiled by the Office of the Clerk of the U.S. House of Representatives (which include more than 170,000 blank, spoiled or otherwise null ballots). That sort of overstatement has long been noted by researchers; the comparisons and charts in this analysis use the House Clerk’s figure, along with data from the International Institute for Democracy and Electoral Assistance and individual nations’ statistical and elections authorities.

Explanation: