The 2020 general election has been underway for quite some time now. According to data compiled by the U.S. Elections Project, nearly 100 million ballots have already been cast prior to election day. However, the timelines for accepting, processing, and counting mail-in ballots vary by state, and some have been contested in the court system, creating circumstances under which confusion regarding the volume and partisan distribution of remaining votes left to be counted could lead to premature and erroneous declarations of victory.

We previously issued a report on this subject, highlighting the competitive states with the biggest differences in Trump/Biden margin between all likely voters and likely voters who were not likely to vote by mail. Here, we update the findings from that report with new data collected over the month of October (between the 9th and 25th of the month) and an updated list of competitive states based on those projected by FiveThirtyEight to be within a ten-point margin as of November 2nd.

The core finding from that report is unchanged. Trump leads in key states among voters who are not very likely to vote by mail, despite Biden leading many of these states overall. This is driven by Biden voters being significantly more likely to say they are either very likely to vote by mail or have already done so.

The two states with black bars -- Wisconsin and Pennsylvania -- are the states that will likely require the most patience over the course of this week, as they will not begin processing ballots received by mail until the morning of election day at the earliest (some counties in Pennsylvania will, at their discretion, not begin counting mailed ballots until Wednesday). While they may be able to count and report some share of ballots sent by mail on election night, it is entirely possible that these states -- especially Pennsylvania, which is closer in pre-election polling -- are not officially called for either candidate until later in the week.

It is also worth keeping in mind that Joe Biden has banked large leads among those who say they have already voted in many of these key states. This is especially apparent in the three states highlighted in the above plot as having limited or no processing of mailed ballots prior to election day: Michigan, Pennsylvania, and Wisconsin. While Biden will win a majority of mailed ballots in these states, he holds commanding margins among mailed ballots that have already been sent and smaller leads among likely voters who say they are very likely to vote by mail but had not done so by the time they responded to our survey. In fact, Biden even trails among this subset of likely voters in Michigan. This means that while the counting of these ballots may be delayed, delays in the mail or legal challenges to late-arriving ballots are less likely to affect the final outcomes -- even if it takes slightly longer to count the mail-in ballots that arrive before states’ deadlines.  

The shares of respondents in each state who fall into each of these categories of voters is shown below, showing that of these states, Michigan reports the highest shares of votes having already been cast. Pennsylvania, followed closely by Michigan, has the highest share of respondents who at the time they took our survey said they had not yet voted but were very likely to do so by mail.

The patterns in these states are similar to those we observe in Arizona, Florida, and North Carolina -- three competitive states that are likely to count and report their mailed-in ballots much more quickly than the states listed above. While one of these states, North Carolina, accepts absentee ballots up to nine days after election day if they are postmarked by election day, each of these competitive states begin processing mail-in ballots well in advance of election day. Moreover, a majority of ballots in these states are likely to have been cast early. Indeed, in North Carolina nearly 62% of registered voters had already voted either early or by mail as of November 1st. We are therefore more likely to know who wins each of these states on election night -- and if Biden wins any of them, the likelihood that he will be able to assemble 270 electoral votes is significantly increased.

Again, we see that Biden banked large leads in these states among voters who said they had already voted when they took our survey between October 9th and 25th -- and held sizable leads in both Florida and Arizona among likely voters who said they were likely to vote by mail but had not yet done so. President Trump will be relying on large election-day margins in these states in order to close this gap.

We again show the shares of respondents in these states who have already voted, plan to do so by mail, and plan to do so in person in the below table for reference. Here, we find that Florida, followed by Arizona, have the highest share of respondents who said they had already voted, and Arizona reporting the highest share of likely voters who said they were very likely to vote by mail but had not yet done so. Of these three states, North Carolina has the lowest such rate, at just 10% of all likely voters.

Finally, we visualize these trends from a different angle by plotting the rates at which Biden and Trump’s supporters said they had already voted -- either in-person or by mail -- in these selected states. Each candidate’s overall share of the vote that we observe in these states is reported at the top of each panel, though for our purposes we are most concerned with the rate at which each candidate has banked support. As the chart shows, more of Biden’s votes have already been cast in each of these competitive states -- more than double the share of Trump’s votes in Pennsylvania and Wisconsin. It is important to clarify that more ballots have come in since the end of our data collection period for both of these candidates, and respondents who took our survey earlier in the period and hadn’t yet voted may have done so shortly thereafter. Which is to say, well over half of Joe Biden’s votes in these states have already been received.

Taken together, these results provide a handful of important points to bear in mind as votes are counted and results come in. First, be patient for results in states that did not start processing mail-in ballots until on or just before election day -- Michigan, Pennsylvania, and Wisconsin. As a larger share of Joe Biden’s voters cast their ballots by mail, Trump may hold a lead in early returns that is not robust to a full ballot count. If Trump declares victory based on these early returns -- as he has signaled he intends to -- it is important for the media and citizens alike to discount it as cheap talk. Second, less patient observers should instead keep their eyes on quicker-counting swing states that have the potential to hold high leverage over the final outcome: Arizona, Florida, and North Carolina. While Biden has multiple paths to victory without these states, Trump does not. If any of them are called for Biden, we could have a clear indication of the winner on election night.