What is "Drop-off"
On December 12, 2024, an organization named Smart Elections released a post on their substack titled Strange Numbers. In a section titled "What is "Drop-off", it states:
What we're presenting today is an analysis of what we call "drop-off."
We measure the difference between the votes for the President and the next down-ballot race, both in raw numbers and in percentages for each major party (Democrat and Republican).
The link at the top takes you to the spreadsheet with the summary data. That spreadsheet is drawn from individual state spreadsheets that we will be releasing shortly both here and on our website SMARTelections.us
Smart Elections also has a page on their website with a section titled "Drop-Off analysis - 2024 ELECTION" which contains the following two plots:
The rightmost plot shows that, taking the swing states as a whole, Democrats had a negative drop-off and Republicans had an especially large positive drop-off. This means that Harris received fewer votes (1.48% fewer) than the Democratic candidate in the down-ballot race but that Trump received noticeably more votes (5.58% more) than the Republican candidate in the down-ballot race. Taking the non-swing states as a whole, however, both Harris and Trump received more votes than their party's down-ballot candidate, 1.37% more for Harris and 2.00% more from Trump. The down-ballot race was usually a Senate race but was occasionally Governor or Attorney General.
To verify this data, the table below compares election data obtained chiefly from the MIT Election Data and Science Lab for 2024 to the Smart Election data in their spreadsheet. The column DOV_Diff shows the differences in the drop-off votes and column DOP_Diff shows the differences in the drop-off percents.
Validating Smart Elections' Data
N ElectionDate State Party US.President DownBallot DOVotes DOV_SE DOV_Diff DOPercent DOP_SE DOP_Diff DB_Race SE.Group
--- ------------ ----- ----- ------------ ---------- ------- ------- -------- --------- ------- -------- ---------------- --------
4 2024/11/05 AZ DEM 1582791 1676315 -93524 -93475 -49 -5.91% -5.91% 0.00% US SENATE 1
5 2024/11/05 CA DEM 9269414 9029588 239826 237965 1861 2.59% 2.59% 0.00% US SENATE 3
7 2024/11/05 CT DEM 992053 953646 38407 -8612 47019 3.87% -0.87% 4.74% US SENATE 3
8 2024/11/05 DE DEM 289758 279585 10173 10173 0 3.51% 3.51% 0.00% GOVERNOR 3
9 2024/11/05 FL DEM 4683038 4603077 79961 79961 0 1.71% 1.71% 0.00% US SENATE 3
11 2024/11/05 HI DEM 313044 324194 -11150 -11150 0 -3.56% -3.56% 0.00% US SENATE 3
15 2024/11/05 IN DEM 1163603 1097061 66542 56542 10000 5.72% 4.90% 0.82% US SENATE 3
19 2024/11/05 MA DEM 2126518 2041668 84850 NA NA 3.99% US SENATE 5
20 2024/11/05 MD DEM 1902604 1650912 251692 251665 27 13.23% 13.23% 0.00% US SENATE 3
21 2024/11/05 ME DEM 430342 86464 343878 NA NA 79.91% US SENATE 5
22 2024/11/05 MI DEM 2736533 2712686 23847 23847 0 0.87% 0.87% 0.00% US SENATE 1
23 2024/11/05 MN DEM 1656979 1792441 -135462 NA NA -8.18% US SENATE 5
24 2024/11/05 MO DEM 1200599 1243728 -43129 NA NA -3.59% US SENATE 5
25 2024/11/05 MS DEM 466667 451980 14687 NA NA 3.15% US SENATE 5
26 2024/11/05 MT DEM 231856 276252 -44396 -44396 0 -19.15% -19.15% 0.00% US SENATE 3
27 2024/11/05 NC DEM 2714494 2874059 -159565 -158677 -888 -5.88% -5.84% -0.04% ATTORNEY GENERAL 1
28 2024/11/05 ND DEM 112327 121602 -9275 -9275 0 -8.26% -8.26% 0.00% US SENATE 3
29 2024/11/05 NE DEM 369995 436493 -66498 NA NA -17.97% US SENATE 5
30 2024/11/05 NH DEM 418488 360149 58339 NA NA 13.94% GOVERNOR 5
31 2024/11/05 NJ DEM 2220713 2161491 59222 NA NA 2.67% US SENATE 5
32 2024/11/05 NM DEM 478802 497333 -18531 NA NA -3.87% US SENATE 5
33 2024/11/05 NV DEM 705057 700976 4081 4092 -11 0.58% 0.58% 0.00% US SENATE 1
34 2024/11/05 NY DEM 4619543 4711669 -92126 -93638 1512 -1.99% -2.13% 0.14% US SENATE 3
35 2024/11/05 OH DEM 2533699 2650949 -117250 -117250 0 -4.63% -4.63% 0.00% US SENATE 3
37 2024/11/05 OR DEM 1236213 1153287 82926 NA NA 6.71% ATTORNEY GENERAL 5
38 2024/11/05 PA DEM 3420865 3382144 38721 38810 -89 1.13% 1.13% 0.00% US SENATE 1
39 2024/11/05 RI DEM 285156 294665 -9509 NA NA -3.33% US SENATE 5
42 2024/11/05 TN DEM 1056265 1027461 28804 NA NA 2.73% US SENATE 5
43 2024/11/05 TX DEM 4835134 5031142 -196008 NA NA -4.05% US SENATE 5
44 2024/11/05 UT DEM 562382 464368 98014 NA NA 17.43% US SENATE 5
45 2024/11/05 VA DEM 2335395 2417115 -81720 NA NA -3.50% US SENATE 5
46 2024/11/05 VT DEM 235791 NA NA NA NA US SENATE 5
47 2024/11/05 WA DEM 2243401 2251055 -7654 NA NA -0.34% US SENATE 5
48 2024/11/05 WI DEM 1668229 1672777 -4548 -4548 0 -0.27% -0.27% 0.00% US SENATE 1
49 2024/11/05 WV DEM 214309 207548 6761 NA NA 3.15% US SENATE 5
50 2024/11/05 WY DEM 69527 63727 5800 NA NA 8.34% US SENATE 5
54 2024/11/05 AZ REP 1770209 1595731 174478 174481 -3 9.86% 9.86% 0.00% US SENATE 1
55 2024/11/05 CA REP 6071718 6302653 -230935 -236519 5584 -3.80% -3.95% 0.15% US SENATE 3
57 2024/11/05 CT REP 736918 678256 58662 59065 -403 7.96% 8.02% -0.06% US SENATE 3
58 2024/11/05 DE REP 214351 219050 -4699 -4699 0 -2.19% -2.19% 0.00% GOVERNOR 3
59 2024/11/05 FL REP 6110126 5977707 132419 132419 0 2.17% 2.17% 0.00% US SENATE 3
61 2024/11/05 HI REP 193661 160075 33586 33586 0 17.34% 17.34% 0.00% US SENATE 3
65 2024/11/05 IN REP 1720347 1659416 60931 60931 0 3.54% 3.54% 0.00% US SENATE 3
69 2024/11/05 MA REP 1251303 1365440 -114137 NA NA -9.12% US SENATE 5
70 2024/11/05 MD REP 1035655 1294344 -258689 -258794 105 -24.98% -24.99% 0.01% US SENATE 3
71 2024/11/05 ME REP 376991 283638 93353 NA NA 24.76% US SENATE 5
72 2024/11/05 MI REP 2816636 2693680 122956 122956 0 4.37% 4.37% 0.00% US SENATE 1
73 2024/11/05 MN REP 1519032 1291712 227320 NA NA 14.96% US SENATE 5
74 2024/11/05 MO REP 1751986 1651907 100079 NA NA 5.71% US SENATE 5
75 2024/11/05 MS REP 747744 763420 -15676 NA NA -2.10% US SENATE 5
76 2024/11/05 MT REP 352001 319618 32383 32383 0 9.20% 9.20% 0.00% US SENATE 3
77 2024/11/05 NC REP 2898099 2715157 182942 183272 -330 6.31% 6.32% -0.01% ATTORNEY GENERAL 1
78 2024/11/05 ND REP 246505 241569 4936 4936 0 2.00% 2.00% 0.00% US SENATE 3
79 2024/11/05 NE REP 564816 499124 65692 NA NA 11.63% US SENATE 5
80 2024/11/05 NH REP 395523 436122 -40599 NA NA -10.26% GOVERNOR 5
81 2024/11/05 NJ REP 1968215 1773589 194626 NA NA 9.89% US SENATE 5
82 2024/11/05 NM REP 423391 405978 17413 NA NA 4.11% US SENATE 5
83 2024/11/05 NV REP 750963 676852 74111 74159 -48 9.87% 9.87% 0.00% US SENATE 1
84 2024/11/05 NY REP 3579519 3246690 332829 318156 14673 9.30% 9.18% 0.12% US SENATE 3
85 2024/11/05 OH REP 3180116 2857383 322733 322733 0 10.15% 10.15% 0.00% US SENATE 3
87 2024/11/05 OR REP 912891 961343 -48452 NA NA -5.31% ATTORNEY GENERAL 5
88 2024/11/05 PA REP 3543041 3399054 143987 144010 -23 4.06% 4.07% -0.01% US SENATE 1
89 2024/11/05 RI REP 214406 196039 18367 NA NA US SENATE 5
92 2024/11/05 TN REP 1966865 1918743 48122 NA NA US SENATE 5
93 2024/11/05 TX REP 6393403 5990637 402766 NA NA US SENATE 5
94 2024/11/05 UT REP 883417 914298 -30881 NA NA US SENATE 5
95 2024/11/05 VA REP 2075085 2019911 55174 NA NA US SENATE 5
96 2024/11/05 VT REP 119395 116512 2883 NA NA US SENATE 5
97 2024/11/05 WA REP 1528208 1547135 -18927 NA NA US SENATE 5
98 2024/11/05 WI REP 1697626 1643996 53630 53630 0 3.16% 3.16% 0.00% US SENATE 1
99 2024/11/05 WV REP 533556 514079 19477 NA NA US SENATE 5
100 2024/11/05 WY REP 192633 198418 -5785 NA NA US SENATE 5
As can be seen, the only percent differences greater than 0.15 percent are 4.74 percent for the Democratic drop-off for Connecticut (CT) and 0.82 for the Democratic drop-off for Indiana (IN). Both of those are shown in red in the table above. The latter error seems to be an error of 10,000 votes in the Smart Elections numbers. The problem appears to be that their spreadsheet lists 1,153,603 for Harris in Indiana but the OFFICIAL 2024 PRESIDENTIAL GENERAL ELECTION RESULTS lists 1,163,603, exactly 10,000 more.
The larger error in Connecticut is interesting. The numbers above of 992,053 and 736,918 for the Democratic and Republican votes in the Presidential election exactly match the OFFICIAL 2024 PRESIDENTIAL GENERAL ELECTION RESULTS. The Smart Elections numbers of 990,946 and 736,559 are just 0.1116% and 0.0487% smaller.
In the Senate race, Wikipedia, NBC News and Fox News all agree that the votes were 1,000,695 for the Democrat and 678,256 for the Republican. The Smart Elections numbers of 999,558 and 677,494 are just 0.1136% and 0.1123% smaller. However, the numbers above from MIT of 953,646 and 678,256 are about 4.7 percent smaller for the Democrat and exactly the same for the Republican. The main page for 2024 MIT data gives the source of the Connecticut numbers to be https://ctemspublic.tgstg.net/#/selectTown. Going to this page and setting 'Select Election' to '11/05/2024 - Presidential Election 2024' (and selecting the Summary tab if necessary) shows the Democrat and Republican numbers to be 953,646 and 678,256 for United States Senator. Hence, even though this page is labelled "Connecticut Secretary of State" and "Official Results", the Democratic number of Senator appears to be about 4.7% off. That is, it appears that the "official results" listed here are in error. Similarly, it is possible that the Indiana error was not an error with Smart Election's quoting of its source but with their source itself.
Smart Elections' spreadsheet lists the percentage of drop-off by state & party in the rightmost set of three columns. Those percentages are shown in column DOP_SE below. Also in the tables below are the percentage of drop-off calculated from the MIT data (column DOPercent) and the difference between that and the Smart Election calculations (column DOP_Diff). As can be seen, there is very little difference between the Smart Election calculations and MIT calculations. As previously explained, the largest difference of 0.21% appears to be largely due to an error in the source for the MIT data for Connecticut.
A "swing state" is defined at this link as follows:
A "swing state" - also referred to as a "battleground state," "toss-up state," or "purple state" - is a state that can be potentially won by (or "swing" to) either the Democratic or Republican presidential candidate, depending on the election. Swing states are usually won by a small margin of votes and could "swing" to a different party than in the previous election.
Smart Elections' analysis of the drop-off in swing states versus non-swing states implies that there is some relationship between drop-off and vote margin. To better judge any possible relationship, the following charts plot the drop-off verus the vote margin by state for the Democratic and Republican presidential candidates in 2024 (top row) and 2020 (bottom row). Any of the charts can be expanded by clicking the "Expand" button near the upper right corner of the chart and the 2 by 2 grid of charts can be returned to by clicking the "Return to grid" button near the upper right corner of the expanded chart.
As can be seen in the top-left chart, the drop-offs for Democratic candidates appear to bow down into negative values near a vote margin of zero. The maximum vote margin of a swing state is not explicitly defined but is often take to be from about 3 to 5 percent. In the chart, the states with small positive margins (up to 6 percent) are Arizona (AZ), Michigan (MI), North Carolina (NC), Nevada (NV), Pennsylvania (PA), and Wisconsin (WI). These are 6 of what were commonly considered the 7 swing states in 2024. The other state, Georgia (GA), does not appear because it had no appropriate down-ballot race. Hence, all 7 swing states went to Trump. There are 5 states that were won by Harris by less than 6 percent but those were not commonly thought of as swing states. Those states were Minnesota (MN), New Hampshire (NH), New Jersey (NJ), New Mexico (NM), and Virginia (VA). Of the 6 swing states, 3 had drop-offs below zero and the other 3 had drop-off below 1.14 percent. And, as mentioned, the drop-off of the states appear to bow with the bottom of the bow around a vote margin of zero.
In contrast, the drop-offs for Republican candidates in the top-right chart appear to bow up into higher postive values near a vote margin of zero. The six swing states have drop-offs ranging from just over 3 for Wisconsin to nearly 10 for Arizona and Nevada. These drop-offs are higher than the historical drop-off from a Presidential race to a corresponding Senate race since 2000, shown in a table in this analysis to have been 2.4 percent. It should be noted that the down-ballot race for North Carolina was the Attorney General race as there was no Senate race in North Carolina in 2024.
In contrast to the charts for 2024, the charts for the drop-offs for Democratic candidates (bottom-left chart) and Republican candidates (bottom-right chart) do not show any noticeable bowing near vote margins of zero. Their distribution appears to be relatively stable around an average of about 2 percent for all possible vote margins. The most noticeable exception might be somewhat higher drop-offs for Democratic candidates in heavily Republican states like Louisiana (LA), North Dakota (ND), Tennessee (TN), Utah (UT), and West Virginia (WV). The table in this analysis lists the average drop-off from a Presidential race to a corresponding Senate race in 2020 to have been 1.4 percent. This would seem to suggest that there may have been something going on in the swing states in 2024 to advantage Trump and/or disadvantage the Democratic Presidential candidate that did not occur, at least to the same degree, in 2020.
The following maps show the drop-off by county in the 2024 and 2020 General Elections. One of the most obvious things in the top maps is that the left (Democratic) map is generally redder than the right (Republican) map. This indicates that the drop-off in Democratic counties in 2024 was generally negative in Democratic counties and positive in Republican counties, especially in swing states. This trend can also be seen in the bottom maps for the 2020 General Election but less so.
The the plots above and the maps below are drawn with Plotly which allows the user to hover the mouse over a county and get a pop-up window that shows a number of values including the state, county, down-ballot race, total votes, and drop-off (as % VOTES). Also, there are Plotly controls above the upper-right corner of the plot that allow the user to download a PNG image, pan across, and zoom in on an image, amoung other functions.
One problem with looking at drop-off by party is that it can be affected by the relative popularity of the candidates. This seems to often occur with moderate Democratic candidates in red states and moderate Republican candidates in blue states. For example, the top left map above shows Montana and Nebraska to be dark red. The negative drop-off in the red state of Montana is likely affected by the popularity of the Democratic Senate candidate Jon Tester who Wikipedia describes at a "moderate Democrat" and says that a New York Times profile described him as "truly your grandfather's Democrat—a pro-gun, anti-big-business prairie pragmatist whose life is defined by the treeless patch of hard Montana dirt that has been in the family since 1916". Similarly, the negative drop-off in Nebraska is likely affected by the relative popularity of the Independent Senate candidate Dan Osborn who, according to Wikipedia "drew attention for his unorthodox, populist platform and his unusually high-level support as a moderate independent candidate in what is usually a strongly Republican state." In contrast, the negative drop-off of the blue state of Maryland shown in the upper-right map is likely affected by the popularity of Larry Hogan, who Wikipedia said was lebeled by media outlets as a "moderate Republican and pragmatist".
Drop-off can also be affected by a strong third party candidate or a missing primary party candidate. For example, dark green color of Maine in the top two maps above are highly affected by the relative weakness of the down-ballot candidates for both parties. This was the 2024 Senate race in Maine which was won by Independent Angus King over much weaker Republican and Democratic candidates. The fact that Vermont is colored in the upper right Republican map but missing in the upper left Democratic map is due to the 2024 Senate race in Vermont being won by Independent Bernie Sanders but having no Democratic candidated.
Similar to the 2024 Vermont Senate race, the 2020 Arkansas Senate race and 2020 Vermont Governor race had no Democratic candidates. Hence, both of those states are missing in the lower left Democratic map for 2020 above. The missing Democratic candidates for Arkansss (AR) and Vermont (VT) can be seen in the lower right bar chart below. Similarly, the upper right bar chart above show a strong third party candidate for Maine (ME) and missing Democratic candidate for Vermont (VT).
Looking at the drop-off in total votes avoids the problem of the drop-off being affected by the relative popularity of the candidates. By looking at ALL of the candidates, only the popularity of the office itself could be said to affect the drop-off. The maps below show the drop-off of the total votes for President to the total votes for the down-ballot race by county. As can be seen, the drop-off is a small positive number in most counties as would be expected. Strangely, most of the counties in Montana and a few others (like Union County in Oregon) in the top map for 2024 are light red, indicating a negative drop-off. This means that, in these counties, more voters voted in the down-ballot race than in the Presidential race on net. This would seem to be a strange thing to happen unless the county had very few votes. If CVRs (cast vote records) can be obtained for any of these counties, it would be interesting to see how many of the ballots which contain a vote for the down-ballot race but not for the Presidential race were "bullet ballots". Those are ballots that contain only one vote, the vote for the down-ballot race. It might also be worth seeing if there is a problem with a badly designed ballot or something else to explain the negative drop-off.
It might similarly be worth looking at the counties that have exceptionally high drop-offs to see if much of that is due to "bullet ballots" for President or a ballot design issue. For the map below for 2024, that might include some of the counties along the southern border of Texas (especially Starr and Zapata County) and some of the darker counties in Indiana.
In the map below for 2020, most of the counties in Montana are light red, just as they were in 2024. However, most counties in South Carolina and many counties in Alabama, Kentucky, and South Dakota are light red indicating negative drop-offs. Starr and Zapata counties have higher than usual drop-offs of nearly 13 and 16 percent. High drop-offs can also be found in several other Texas counties (Duval, Kenedy, and Culberson Counties and Uintah County in Utah and some others. It might be likewise useful to look for the role of "bullet ballots" in these counties, if possible, or the roll of ballot design or other factors.
Validating Smart Elections' Calculations
SWING STATES (MINUS GA)
ElectionDate Party US President DownBallot DOVotes DOPercent DOP_SE DOP_Diff
------------ ----- ------------ ---------- --------- --------- ------ --------
2024/11/05 DEM 12,827,969 13,018,957 -190,988 -1.49% -1.48% 0.01%
2024/11/05 REP 13,476,574 12,724,470 752,104 5.58% -5.58% 0.00%
NON-SWING STATES (SMART ELECTIONS)
ElectionDate Party US President DownBallot DOVotes DOPercent DOP_SE DOP_Diff
------------ ----- ------------ ---------- --------- --------- ------ --------
2024/11/05 DEM 26,110,939 25,698,535 412,404 1.58% 1.37% 0.21%
2024/11/05 REP 23,440,917 22,956,761 484,156 2.07% 2.00% 0.07%
NON-SWING STATES (ALL)
ElectionDate Party US President DownBallot DOVotes DOPercent DOP_SE DOP_Diff
------------ ----- ------------ ---------- --------- --------- ------ --------
2024/11/05 DEM 49,728,926 47,680,650 2,048,276 4.12% NA NA
2024/11/05 REP 47,259,777 45,804,806 1,454,971 3.08% NA NA
The last table titled "NON-SWING STATES (ALL)" shows the drop-offs if all non-swing states are included, not just the 10 included in the Smart Elections calculations.
Plotting Drop-off versus Vote Margin
Mapping Drop-off by County
Effect of Strong Third Party or Absent Primary Party Candidate
Mapping Drop-off in Total Votes
2024 U.S. Election