Nearly three-quarters of his donors were in New York State — yet a dozen candidates had more donors from the state than Mr. de Blasio (including Senator Kirsten Gillibrand of New York, who ranked sixth in the state ).

In the ZIP code that includes Gracie Mansion, the mayor’s residence on the Upper East Side of Manhattan, Mr. de Blasio had roughly the same number of donors as Mr. Bullock and former Gov. John Hickenlooper of Colorado. About 26 people in that ZIP code gave to Mr. Buttigieg for each person who gave to Mr. de Blasio.

Mr. de Blasio did little better in his former Park Slope neighborhood — the ZIP code where support for Ms. Warren was abundant. Mr. de Blasio had roughly the same number of donors as Senator Michael Bennet of Colorado, and he trailed, among others, Gov. Jay Inslee of Washington, Andrew Yang and Marianne Williamson.

Small donors are flocking to Sanders and Warren.

Mr. Sanders and Ms. Warren are both attracting lots of small donors, reflected in the average amount they each received from their donors. We estimated that Mr. Sanders’s donors gave him an average of $46, and Ms. Warren’s gave her $53. (Many donors make multiple contributions in even smaller amounts.)

Those were among the smallest donor averages in the Democratic field. The only candidates to receive a smaller amount from their donors were Mr. Yang, at $40 per donor; Representative Tulsi Gabbard of Hawaii, at $38 per donor; Mr. Castro, at $36 per donor; and Ms. Williamson, at $33 per donor.

Mr. Sanders’s lower donor average explains why he has a huge lead in donors but a less imposing lead in the total amount of money raised. By contrast, the No. 2 candidate in total money raised, Mr. Buttigieg, has received an estimated average of $76 from his donors. Senator Kamala Harris of California has received $81 per donor, and Mr. Biden has received $82.

John Delaney, a former Maryland congressman who is largely self-financing his campaign, received the most money per donor: an estimated average of $235.