The New York City Council on Tuesday voted 45 to 4 to pass legislation lowering the city's default speed limit from 30 to 25 miles per hour.

Speaker Melissa Mark-Viverito said it was the thirteenth bill the Council had passed this year in support of Mayor Bill de Blasio's Vision Zero initiative, and many supporters say it's the most important.

"Speed is the single greatest contributing factor in New York City traffic deaths," Mark-Viverito said. "This critical change in our traffic code can change countless lives."

"To have a piece of legislation that will save lives — that's unique," said Councilmember David Greenfield, the lead sponsor of the bill, before the vote. "That's something that's not normally within our bailiwick."

The last time the city's speed limit was officially changed was in 1964, when it was increased to 30 mph. "To put that in context," said Greenfield, "the bus and train fares at the time were 20 cents."

Paul Steely White, the head of Transportation Alternatives, hailed the legislation. "If properly enforced," he said in a statement, "the new speed limit could prevent more than 6,500 traffic injuries in the next year and cut the annual number of pedestrian fatalities in half."

Mayor Bill de Blasio is expected to sign the legislation. It will go into effect November 7.