Voter turnout in U.S. presidential elections has not exceeded 60% of the voting-age population since 1968.
In 2016, just 55.7% of eligible voters turned out in an election decided by a few thousand votes in a few key states. Recently, only the 2008 election between Barack Obama and John McCain resulted in voting that even approached the 60% threshold (58.2%). But that level dropped back down to 54.9% in 2012. Will the 2020 election generate enough enthusiasm (on both sides) to boost turnout close to the 60% level?
There's a chance, due to a few important factors. The severe polarization in the electorate will likely excite the respective partisan bases—although most polling shows an "enthusiasm gap" in favor of President Trump. The selection of Kamala Harris as Joe Biden's running mate may be a way for Democrats to close that gap—if women and minorities are sufficiently excited by that historic selection. And, a range of issues that have directly affected the daily lives of most Americans will be front and center in the race—most prominently the pandemic and its impact on the economy. That type of issue personalization often results in higher turnout.
On the other hand, a number of factors mitigate against higher turnout. First and foremost is the impact of the COVID-19 pandemic on voter participation. Will universal and absentee mail-in voting be accepted by voters who are wary of showing up at their polling place in person? Or will they just (quite literally) sit out the race? And, will a bitterly-fought (and likely ugly) campaign turn off voters enough to tamp down participation on election day?
The U.S. voting age population has grown to about 255 million in 2020. That means that to even equal the 2016 turnout of 55.7%, a bit over 142 million Americans will have to exercise their franchise. That's a tall order—adding about five million more voters from the 2016 level.
Of course, the national numbers don't really matter that much. What's really important is where turnout happens—particularly in swing states like Pennsylvania, Ohio, Wisconsin and Michigan. Both parties will surely be targeting heightened turnout in those critical areas. The success of these efforts will ultimately depend upon whether Americans care enough to show up (either in-person or otherwise) on November 3rd.