The 2020 Iowa Democratic presidential caucuses, the first nominating contest in the Democratic Party primaries for the 2020 presidential election, took place on February 3, 2020. Pete Buttigieg received the most state delegate equivalents (SDEs) and therefore the most delegates, with one SDE and two delegates more than Bernie Sanders, who had narrowly won the popular vote with 26.5%, 1.5% ahead of Buttigieg. It was the first time that the Iowa caucuses published the popular vote results of their contest. Buttigieg became the first openly gay person to ever earn the most delegates in a state's presidential contest in the United States. The Iowa caucuses were closed caucuses, wherein only registered members of a party were eligible to vote, and awarded 49 delegates to the 2020 Democratic National Convention, of which 41 were pledged delegates allocated on the basis of the results of the caucuses.

The 2020 Iowa Democratic caucuses were controversial due to the delays in reporting the results. These delays, caused in part by problems with a mobile application created by Shadow Inc. that was used to report voting totals, led to the resignation of Iowa Democratic Party chair Troy Price. Further controversy resulted from errors and inconsistencies regarding the calculation and reporting of State Delegate Equivalents (SDEs) in several caucus locations. Following a three-day delay in vote reporting, the Iowa Democratic Party declared that Buttigieg had won two more delegates than Sanders.

The official result and calculation of pledged national convention delegates was delayed until six days after the election due to the need for a correction of reported results from 3.1% (55) of the precincts. Buttigieg and Sanders then requested a partial recanvass for 8.1% of the official result, which resulted in Buttigieg's lead over Sanders narrowing to 0.08 SDEs. A final recount for 63 of the recanvassed precincts (3.6% of all results) was requested by both campaigns on February 19. Two days later, the Iowa Democratic Party announced that it had accepted recount requests for 23 precincts (1.3% of all results). The recounts took place from February 25 to February 27, with the Iowa Democratic Party announcing the results of the recounts on February 27, 2020. The results were certified by the state committee on February 29. The Associated Press at that point still refused to call a winner due to too many discrepancies in the precinct vote records, though they acknowledged the official results in their delegate count, and Sanders challenged the results after certification before the DNC Rules and Bylaws Committee, but there were no media reports about the outcome of that challenge.

Despite his underperformance, Joe Biden would go on to win the nomination, becoming the first Democratic candidate to do so without winning Iowa since Bill Clinton in 1992. Additionally, with Biden defeating incumbent president Donald Trump in the general election, he became the first candidate to do so without finishing in the top 3 in Iowa since the inception of the caucuses in 1972. The vote counting issues led to Iowa being stripped of their first in the nation position for 2024.

Procedure

As the event was a closed caucus, only Iowans registered as Democrats could vote. However, Iowans who did not register as Democrats before the caucus day could still register as such on caucus night itself at their designated precinct, thereby gaining full voting rights at the event. The votes were cast by physically standing in a section of the caucus site corresponding to the preferred candidate. Proxy voting or absentee voting (i.e. by mail or through participation in a preceding "virtual caucus") was not allowed.

1,678 Iowa precinct caucuses and 87 satellite caucuses around the world (organized as alternative voting sites for registered Democratic Iowans who were unable to vote locally at their precinct caucus) were held, with doors being closed at 7:00pm CST on February 3, 2020, in order to elect precinct delegates for the subsequent county conventions and allocate the state's 41 pledged national convention delegates based upon the proportional accumulative result of all the precincts.

Precinct caucus procedures

In all precinct caucuses that elect more than one county convention delegate, the presidential candidates must meet a viability threshold within the individual precinct in order to qualify as a viable candidate. The thresholds are: a minimum of 25% for precincts electing only two delegates; a minimum of 16.66% for precincts electing only three delegates; and a minimum of 15% for the majority of precincts electing more than three delegates.

After the first round of voting, supporters of viable candidates have their votes locked to their chosen candidate, while the supporters of nonviable candidates are allowed through a second final round of voting (called realignment) to transfer their vote either to an alreadyviable candidate or to a nonviable group as long as they make it viable. If the number of viable groups formed in the first round or final round exceeds the number of electable county convention delegates in the precinct, then the smallest viable group(s) are forced to realign until the number of viable groups no longer exceeds the number of delegates. Precinct caucuses that elect a single county convention delegate have no viability threshold and thus do not need to go through realignment, but instead elect their single delegate based upon a simple majority vote expressed by the "first alignment" round.

After the final realignment round has ended and the correct maximum number of viable groups formed, then each of those viable groups (supporting a candidate or being uncommitted) elects the county convention delegate(s) their group won according to its proportional percentage share of the qualified votes won after the final alignment in the local precinct. However, due to rounding errors, it is still possible, by following the outlined calculation procedure, that the total number of county convention delegates awarded by the precinct will be higher or lower than the delegate number to which the precinct is entitled. Therefore, as a last correctional step, the viable groups might also gain or lose a delegate depending on the size of their calculated delegate fraction before rounding in order to compensate for the rounding issue. In this last correctional rounding procedure, a special rule ensures that a group can never lose its only county convention delegate won (meaning that a fractional 0.5 delegate calculated to have been won by a group will always be rounded up to one, even when other larger groups are calculated to have higher fractions).

A summary in the table below, display the ratio between state delegate equivalents (SDE's) and county convention delegates (CCD) for all of Iowa's 99 counties. Each county has a different SDE ratio per county convention delegate, with the most populous counties having the highest SDE ratio and the least populous counties having the lowest SDE ratio. The ratio is used when each county converts the results of won county convention delegates into the number of won SDE's. The use of a different ratio in each county mean, that some county convention delegates will be counted to be more worth in SDE-terms compared to their fellow county convention delegates elected in other counties (similar to the principle of the United States Electoral College, where it is possible to win the popular vote without winning the race deciding delegate count).

County convention delegates and SDEs County Precincts SDE/CCD ratio Adair CD3 5 51 4 0.078 Adams CD3 5 35 3 0.086 Allamakee CD1 11 90 7 0.078 Appanoose CD2 12 75 6 0.080 Audubon CD4 2 30 3 0.100 Benton CD1 19 200 15 0.075 Black Hawk CD1 62 500 101 0.202 Boone CD4 15 100 19 0.190 Bremer CD1 13 75 17 0.227 Buchanan CD1 15 95 13 0.137 Buena Vista CD4 10 45 9 0.200 Butler CD4 8 60 7 0.117 Calhoun CD4 10 60 5 0.083 Carroll CD4 13 100 11 0.110 Cass CD3 12 50 6 0.120 Cedar CD2 12 70 12 0.171 Cerro Gordo CD4 26 175 31 0.177 Cherokee CD4 7 55 6 0.109 Chickasaw CD4 13 100 7 0.070 Clarke CD2 7 50 4 0.080 Clay CD4 12 85 8 0.094 Clayton CD1 14 60 10 0.167 Clinton CD2 26 140 31 0.221 Crawford CD4 8 40 6 0.150 Dallas CD3 34 140 58 0.414 Davis CD2 8 100 3 0.030 Decatur CD2 7 85 4 0.047 Delaware CD1 12 120 9 0.075 Des Moines CD2 16 75 27 0.360 Dickinson CD4 15 80 10 0.125 Dubuque CD1 35 270 72 0.267 Emmet CD4 11 35 4 0.114 Fayette CD1 25 100 12 0.120 Floyd CD4 8 90 10 0.111 Franklin CD4 12 90 5 0.056 Fremont CD3 5 40 3 0.075 Greene CD4 7 50 6 0.120 Grundy CD4 7 60 6 0.100 Guthrie CD3 8 70 6 0.086 Hamilton CD4 8 90 9 0.100 Hancock CD4 10 50 5 0.100 Hardin CD4 8 125 9 0.072 Harrison CD4 13 75 7 0.093 Henry CD2 9 150 10 0.067 Howard CD1 9 35 5 0.143 Humboldt CD4 9 45 4 0.089 Ida CD4 7 20 3 0.150 Iowa CD1 11 100 10 0.100 Jackson CD1 16 70 12 0.171 Jasper CD2 20 200 23 0.115 Jefferson CD2 12 55 12 0.218 Johnson CD2 57 400 162 0.405 Jones CD1 14 75 12 0.160 Keokuk CD2 15 35 4 0.114 Kossuth CD4 20 90 8 0.089 Lee CD2 22 150 21 0.140 Linn CD1 86 430 189 0.440 Louisa CD2 5 50 5 0.100 Lucas CD2 7 55 4 0.073 Lyon CD4 8 30 3 0.100 Madison CD3 9 75 9 0.120 Mahaska CD2 11 50 8 0.160 Marion CD2 17 100 18 0.180 Marshall CD1 19 150 24 0.160 Mills CD3 11 45 7 0.156 Mitchell CD1 12 80 6 0.075 Monona CD4 11 80 4 0.050 Monroe CD2 7 65 3 0.046 Montgomery CD3 7 50 4 0.080 Muscatine CD2 23 150 25 0.167 O'Brien CD4 9 55 4 0.073 Osceola CD4 8 30 3 0.100 Page CD3 8 75 6 0.080 Palo Alto CD4 6 60 5 0.083 Plymouth CD4 13 40 9 0.225 Pocahontas CD4 7 50 3 0.060 Polk CD3 177 1,401 392 0.280 Pottawattamie CD3 46 400 48 0.120 Poweshiek CD1 9 100 14 0.140 Ringgold CD3 7 80 3 0.038 Sac CD4 9 60 4 0.067 Scott CD2 63 300 124 0.413 Shelby CD4 9 100 5 0.050 Sioux CD4 16 80 7 0.088 Story CD4 43 200 83 0.415 Tama CD1 15 85 11 0.129 Taylor CD3 7 30 30.100 Union CD3 8 80 6 0.075 Van Buren CD2 8 30 3 0.100 Wapello CD2 22 200 18 0.090 Warren CD3 31 150 35 0.233 Washington CD2 10 70 13 0.186 Wayne CD2 4 40 3 0.075 Webster CD4 28 240 20 0.083 Winnebago CD4 10 40 6 0.150 Winneshiek CD1 11 125 16 0.128 Woodbury CD4 44 240 51 0.213 Worth CD1 7 75 5 0.067 Wright CD4 10 45 6 0.133 Total 4 1678 11,402 2,107 0.185

Satellite caucus procedures

For the first time in the history of the Iowa caucuses, satellite caucuses around the world (60 in-state and 27 out-of-state) were all organized on election day February 3, as alternative voting sites for registered Democratic Iowans who were unable to vote locally at their precinct caucus. The list below display all types of satellite sites (of which most were open for participation of all Iowans, while some were closed caucuses only for those with a private residence or workplace affiliation): 14 working-related sites 24 student sites on college campuses 29 sites accommodating accessibility needs (including aging service centers) 11 sites accommodating language and culture needs 9 out-of-state sites accommodating Iowans wintering in another state

Doors at most satellite caucuses closed at 7:00 pm CST; while some satellite caucuses however closed doors a few hours earlier or later (between 10 am to 8:30 pm CST of the same day).