Preliminary results indicate San Francisco voters voted overwhelmingly in favor of Prop C to raise the affordable housing requirement for new projects from 12% to 25%. Developers previously warned the increased burden would slow construction and exacerbate the housing crisis.

The hotly contested proposal was authored by Supervisors Jane Kim and Aaron Peskin. Mayor Ed Lee asked for more time to study the increase's effect before putting the question to voters.

Some developers opposed the measure, saying it would place a chill on new construction since the proposition would significantly change the economics of a project to reserve 25% of units for below-market-rate housing.

The San Francisco Planning + Urban Research Association (SPUR) gave no recommendation on the proposition. "We debated this measure extensively but were ultimately unable to resolve our conflicting opinions about it," it said in a voter guide. While SPUR acknowledged the risk to development, it suggested the writing allowed wiggle room for the future. "We deeply appreciate that Prop C’s sponsors proposed enabling future boards of supervisors to alter the measure."

SF Bay Area Renter’s Federation principal Sonja Trauss said the move was harmful for renters. "Prop C is a bad idea because increasing the inclusionary rate will reduce the overall amount of housing built by 13.5% and increase displacement by 4%," she told Bisnow. "The more we keep production going, the longer price weakening could last. But now Peskin and Prop C are going to rein in that rent dampening. "