Supervisor Photo-Finishes Gradually Taking Shape

Sometimes, San Francisco does things the slow way. Case in point: last week's races for neighborhood supervisors, which are only just now starting to zero-in on the winners.

The City uses a somewhat more elaborate system than most to elect its leaders: Ranked-Choice Voting. Simply put, the system allows voters to specify second and third choices for each race. As low-ranking candidates are eliminated, voters' backup choices gain votes. The process continues until someone gets more than 50 percent of the vote.

So far, it's a nail-biter in a couple of neighborhoods.

District 2, at the northern end of The City, has Janet Reilly ever so slightly behind Mark Farrell. In the Tenderloin and SOMA, Debra Walker has fallen behind Jane Kim. And Scott Wiener has pulled ahead of Rafael Mandelman in the Castro. District 10, the Bayview, has Malia Cohen ever-so-slightly ahead of Tony Kelly. All of those margins are pretty close.

The ranked-choice system might be statistically efficient, but it has a way of drawing out the suspense. At the Department of Elections, everyone's been nervously pacing as results trickle out. Updates are released electronically before they're printed out, so everyone's been consulting their phones and iPads -- no easy task in City Hall, a notorious dead zone for WiFi and cellular service.

At this point, absentee and provisional ballots could make all the difference. Provisional ballots are handed out to people whose right to vote is in doubt, such as people in hospitals and jails. The legitimacy of the ballot is determined later.