This is The Sprint for City Hall, a limited-run series on the critical Democratic primary race for mayor.

Primary Day has arrived.

Hi, I’m Dean Chang, the editor running The New York Times’s coverage of the mayoral primary. This was to be the eighth and last version of the newsletter, but just when I thought I was out, they pulled me back in — or so it seems.

In this edition, we’ll look at some of the important story lines that might influence the outcome and examine how a campaign’s ground game could make the difference. We’ll also explain why we probably won’t know who won the primary until next Tuesday, which likely extends The Sprint’s life for at least another week. (Any longer and we’re going shopping for a new name.)