Consistent with the data reported above, the average precinct saw 20 people in line when the doors opened on Election Day 2018. By the end of the first hour, that number had been more than cut in half, to 8.6. Even though there was a small surge toward the end of the day, the average in any hour was never as great as it was in the first hour of voting.

The data plotted in Figure 14 that show the variability of line lengths each hour help to round out the picture. Note that the median and mean at opening time are relatively close (median = 14 and mean = 20), which indicates that line lengths across precincts in the study occurred fairly symmetrically. Even by the end of the first hour, the median (2) is quite far from the mean (8.6). Also note that the 90th percentile value at the end of the first hour (25) is far above the mean. This pattern holds from Hours 1 to 13. Statistically, this shows that a small number of outlier precincts with exceptionally long lines heavily influence the average line length after the first hour. The typical precinct has only a handful of people waiting to check in—the median is no more than three people in line after the opening. Finally, it is notable that the variance of line lengths increases dramatically between Hours 9 and 11. Again, because the mean and median are not affected much, this shows that extraordinarily long lines to vote in the hours after work are rare, even if they are troubling.

6. If a precinct clears its morning line quickly, it is unlikely to experience long wait times for the rest of the day. If the morning line persists, long wait times are likely to occur for the entire day.

There is a crush of morning voting on Election Day. The BPC/MIT Polling Place Line Study shows the importance of clearing that morning line. A high volume of voters at the start of the day—both those waiting when the polls open and those coming soon after they open—will lead to lines at most precincts. However, most of those precincts showed the ability to clear those lines within the first couple of hours of voting, never to experience them again for the rest of the day. Conversely, the precincts that could not clear their morning lines after a couple of hours were highly likely to see long lines and long wait times until they closed their doors, often hours after the official polling place closing time. Do long lines early in the day make a precinct more likely to be burdened by long lines after 5 p.m.? Does having a long line right now mean that a precinct is likely to have one in two or six hours?

Overall, the data suggest that the answers to these questions are no to the first and yes to the second. While precincts that have long lines right when the polls open are slightly more likely to have long lines later in the day, most precincts with long lines at the opening see those lines recede fairly quickly. However, as the day progresses, if a precinct has a long line later in the morning or in the afternoon, it is unlikely the lines will shorten appreciably until closing time.

The graphs in Figure 15 illustrate these points. This figure has 12 graphs. Each graph shows the average number of people in line later in the day, broken down by whether there were 20 or more people in line at that hour or less than 20 people in line. For instance, the very first graph charts the average number of people in line each hour for the rest of the day, for precincts that had 20 or more people in line when the polls opened (“Yes”) and for precincts that had fewer than 20 in line (“No”). In these precincts, if there were at least 20 people in line when the polls were open, there are an average of 16.4 in line at the end of Hour 1, 11.6 in line at the end of Hour 2, etc. In contrast, if there were fewer than 20 people in line when the polls opened, there was an average of 3.1 and 2.8 in line at the end of Hours 1 and 2, respectively.

Scanning across all the graphs, notice that the circles in red climb from one graph to the next. This shows that as the day progresses, having 20 or more people in line at any moment portends longer and longer lines down the road. For instance, in precincts that have more than 20 people in line when the polls open, the average line length at the end of Hour 4 is 10.8 people. However, in precincts that have more than 20 people in line at the end of Hour 1, the average number of people in line at the end of Hour 4 rises to 20.8. If there are still more than 20 people in line at the end of Hour 2, the average number in line at the end of Hour 4 rises again to 28.4.

This shows how precincts very quickly diverge in the morning according to two paths: those that can get the lines under control within an hour or two and those that cannot.