It’s official. This morning, Mayor Bill de Blasio, surrounded by administration appointees, elected officials from the City Council and state legislature, and families of traffic violence victims, signed legislation that lowers New York City’s default speed limit to 25 mph. The law takes effect November 7.

Before the bill signing, de Blasio crossed Delancey Street near where a driver killed 12-year-old Dashane Santana in 2012. DOT modified the street’s design later that year in response to her death. Today, de Blasio called for more. “We have to do a lot of work to fix conditions like this across the city,” he said. “It can be done, but it begins with reducing speeding.”

Transportation Commissioner Polly Trottenberg noted that 50 years ago this month, the state legislature raised the default speed limit from 25 to 30 mph. “With this history in mind, it is so nice to be here today having a chance to right this historical wrong,” she said, “and lower the speed limit back to 25 miles per hour.”

Council Member David Greenfield proposed lower speed limit legislation in the City Council in 2013. “This is literally the linchpin of Vision Zero,” he said. “When you drive slower, you can stop faster.”

Under the new law, DOT will be able to sign streets on a case-by-case basis for speed limits other than 25 mph. Trottenberg has said that DOT will set higher speed limits for some major streets, but has not clarified which ones will be exempt from the new 25 mph limit. Earlier this year, DOT refused to lower the speed limit on Queens Boulevard as part of its “arterial Slow Zone” program.

A speed limit is only as good as the education and enforcement behind it. Trottenberg said DOT will be adding or replacing 3,000 signs across the city, including where drivers exit highways, to inform them of the new law. DOT and NYPD will also educate motorists using electronic signs and by handing out flyers, with a major push across the city on Thursday. NYPD Transportation Chief Thomas Chan said precinct officers will also be out with speed guns to enforce the new limit.

A major part of enforcement is speed cameras. The city is still in the process of slowly rolling out the 140 highly-restricted school zone speed cams approved by the state earlier this year. De Blasio’s Vision Zero Action Plan calls for home rule over automated enforcement. Today, the mayor reaffirmed his support for home rule but wouldn’t say if the city will push for it next year in Albany. “This is one of the areas where I think it would be more appropriate for the city to have more say over its own destiny,” he said. “That’s certainly something I’ll continue to pursue.”

If there is a renewed push for automated enforcement in Albany, Families for Safe Streets is likely to again have a big role in working with legislators. “It could have been anyone,” said Amy Cohen, whose son Sammy Cohen Eckstein was killed by a driver a year ago. “In a simple trick of timing, we were the unlucky ones.”

Assembly Speaker Sheldon Silver said meeting the Cohen-Ecksteins and other families helped propel his commitment to lowering the speed limit. “Needless to say, their stories were heartbreaking. I promised these families we would pass legislation,” he said. “We kept the promise.”

The advocacy of traffic violence victims has swayed more than just politicians in Albany. This morning, de Blasio looked back on his days as a council member. “If you had asked me back then, I would’ve said a lot of people would’ve been resistant [to a 25 mph limit]. I myself had a car, drove my car frequently, knew a lot of people who drove cars,” he said. “What’s happened is, over time the toll that these crashes have taken has really affected the thinking of New Yorkers.”

Earlier this month, a driver killed a woman crossing Canal Street, which already has a 25 mph speed limit. Today, a reporter said a Chinese-language newspaper used the death to question the wisdom of a lower speed limit. She asked de Blasio for his opinion. “When we’re talking about matters of public safety, our friends in the media need to be a little more careful,” de Blasio said. “There are many tools in the fight against reckless driving. The speed limit is one of them. Street design is another, speed bumps are another, speed cameras are another, enforcement is another, education is another. You need all these tools. No one said there’s a magic bullet.”

Magic bullet or not, the mayor made sure to highlight that traffic fatalities that are down 7 percent so far this year compared to the year before. The gains are mostly attributable to a drop in pedestrian fatalities, which are down 20 percent. Unmentioned by the mayor: Bicyclist fatalities have doubled over the same period. I asked what the administration is doing to improve bike safety. Turns out the press corps isn’t the only institution with room for improvement.

De Blasio acknowledged that motorists striking bicyclists is the primary threat to bike safety and that increased enforcement against drivers who speed and fail to yield will also benefit bicyclists. He then pivoted to the administration’s efforts to ticket bike riders.

“We also know that there are some bicyclists who have acted inappropriately, and we have increased enforcement activity towards them,” he said. “This is going to be equal opportunity.”

NYPD’s Chan followed up by promoting helmet use and highlighting Operation Safe Cycle, which issued 4,300 tickets to cyclists, often for the least dangerous offenses, and 3,200 to drivers for violations like blocking the bike lane.

Notably missing from today’s event: Police Commissioner Bill Bratton. Although de Blasio called him “a very strong and early voice” on traffic safety, the only presence from the city’s top cop today, as with most Vision Zero initiatives, was a quote in the mayor’s press release.