That’s because in 2016, former Secretary of State Hillary Clinton edged out Senator Bernie Sanders of Vermont in the state delegate count by a quarter of a percentage point, earning roughly 700 to Mr. Sanders’s 697. That meant 23 national delegates for Mrs. Clinton and 21 for Mr. Sanders — an inconsequential difference between the two rivals.

Mr. Sanders’s 2016 campaign fought for an audit in Iowa — comparing the reported results with the papers on which caucus leaders had recorded voters’ preferences — and accused the state Democratic Party of a lack of transparency.

Largely because of Mr. Sanders’s objections, the party decided to release additional numbers in 2020 that it had always logged but never made public: the number of supporters each candidate had in the first round of voting and the number he or she had in the second round, after nonviable candidates were eliminated and caucusgoers realigned.

The idea was that all this data would provide a fuller picture of each candidate’s strength.

Under the old reporting system, for instance, a candidate who received 14 percent support — just below the threshold for earning delegates — would be indistinguishable from a candidate who received 1 percent support. But in the raw vote totals, they could get credit for the support they had in the first round — and in a state where perceptions of strength and political momentum matter much more than delegates, that sort of credit can be crucial.

So the caucuses go: They have always been more about creating momentum (or the perception of it) for candidates than about the number of delegates they award. Iowa’s contribution to a candidate’s total number of delegates is trivial. But the state’s contribution to popular conceptions of political viability is immense.