Skip to Content
Streetsblog USA home
Streetsblog USA home
Log In
Pedestrian safety

3 Graphs That Explain Why 20 MPH Should Be the Limit on City Streets

Graph: ProPublica
A still from ProPublica's interactive graph.
Graph: ProPublica

Speed kills, especially on city streets teeming with pedestrians and cyclists.

The investigative news nonprofit ProPublica has produced an interactive graph that deftly conveys how just a few miles per hour can spell the difference between life and death when a person is struck by a motorist. ProPublica's Lena Groeger used data from the AAA Safety Foundation to chart the plummeting likelihood of survival as motorist speed increases.

The average pedestrian struck by a driver traveling at 20 mph has a 93 percent chance of surviving. For a 70-year-old, the chances are somewhat lower but still a robust 87 percent.

As Groeger puts it:

Once cars reach a certain speed (just above 20 mph), they rapidly become more deadly. According to [AAA's Brian] Tefft's data, a person is about 70 percent more likely to be killed if they’re struck by a vehicle traveling at 30 mph versus 25 mph.

In collisions at 30 miles per hour, about one in five pedestrians will not survive. For older pedestrians, the odds are significantly worse:

Graph: ProPublica
Graph: ProPublica
Graph: ProPublica

The risk of death continues to rise dramatically as speeds exceed 30 mph. At 40 mph, most older pedestrians will not survive:

Graph: ProPublica
Graph: ProPublica
Graph: ProPublica

In addition to much higher survival rates in the event of a collision, driving at slower speeds reduces stopping distances, making it easier for drivers to avoid hitting people in the first place.

These graphs are a compelling visualization of the data that undergirds campaigns like "20's Plenty" in the UK, where residents have demanded 20 mph streets to protect the most vulnerable. As of last fall, more than 14 million people in the UK lived on streets with 20 mph speed limits, according to 20's Plenty founder Rod King, and the campaign is now focused on extending the 20 mph limit to most streets in the country:

Stay in touch

Sign up for our free newsletter

More from Streetsblog USA

Friday Video: The London Neighborhood Where Bikes Outnumber Cars

...and how they got to that impressive milestone.

July 11, 2025

Friday’s Headlines Battle Galactus

Like the Marvel supervillain, U.S. interstate highway system seems to eat up everything in his path. A new book explores how to stop it.

July 11, 2025

New Report Shows Pedestrian Fatalities Drop — But Experts Say Not Enough

The Governors Highway Safety Association report showed a 4 percent drop in the number of pedestrian deaths last year, putting a slow on a dangerous trend — but advocates say the drop isn't nearly big enough.

July 11, 2025

Talking Headways Podcast: Localities Subsidize the State DOT

Adie Tomer of Brookings on how to improve regional coordination around infrastructure.

July 10, 2025

Five of the Ugliest Transportation Policies In the ‘Big, Beautiful’ Bill

Here's a rundown of some of the transportation provisions in the Republicans' reconciliation package, and what they might mean for your community.

July 10, 2025

Viva La Thursday’s Headlines

Why is French transit ridership up 10 percent since before the pandemic, while American transit ridership is down 23 percent?

July 10, 2025
See all posts