An Astounding Explanation for Why Big Cities Are More Dangerous Than Small Ones

For decades, researchers have hunted for an explanation for why big cities have been more prone to violent crime than small ones. A new hypothesis may offer a surprising answer, and prove that big cities aren't inherently much more dangerous.

2 minute read

January 11, 2013, 12:00 PM PST

By Jonathan Nettler @nettsj


Traffic Jam 1970s

Jim Pickerell / Wikimedia Commons

Researchers have offered several potential explanations for historically higher rates of violent crime in big cities: from the idea that there's more valuable stuff to steal in big cities to the rise of the crack epidemic. Even if other potential reasons strike you, you probably haven't considered a new persuasive hypothesis: exposure to gasoline lead. In an article for Mother Jones and in a follow-up blog piece, Kevin Drum examines the connection between lead exposure and crime.

"In a nutshell, the lead-crime hypothesis is simple: exposure to gasoline lead in small children produces heightened aggressive tendencies. When an entire generation of children was exposed to lead in the 40s, 50s, and 60s, thanks to the boom in auto sales after World War II, it led to a huge rise in violent crime when the children grew up in the 60s, 70s, and 80s. The more lead they were exposed to, the more crime you got."

"So where did we see the most exposure to gasoline lead? Answer: in places with the densest concentration of automobiles. And that's in the inner core of big cities. In the early 60s, big cities had double the ambient air lead levels of mid-size cities, which in turn had air lead levels 40 percent higher than small cities. (Nevin, p. 316.) So if lead exposure produces a rise in crime, you'd expect to see a bigger rise in big cities than in small ones. Over time, big cities would become increasingly more dangerous than small ones."

"Likewise, when lead was removed from gasoline, and children started to grow up normally, you'd expect to see a bigger crime decrease in big cities. Over time, crime rates would start to converge."

"And that's exactly what we see in the data."

"Only gasoline lead," concludes Drum in his article, "with its dramatic rise and fall following World War II, can explain the equally dramatic rise and fall in violent crime."

Friday, January 11, 2013 in Mother Jones

portrait of professional woman

I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching. Mary G., Urban Planner

I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching.

Mary G., Urban Planner

Cover CM Credits, Earn Certificates, Push Your Career Forward

Logo for Planetizen Federal Action Tracker with black and white image of U.S. Capitol with water ripple overlay.

Planetizen Federal Action Tracker

A weekly monitor of how Trump’s orders and actions are impacting planners and planning in America.

July 16, 2025 - Diana Ionescu

Green vintage Chicago streetcar from the 1940s parked at the Illinois Railroad Museum in 1988.

Chicago’s Ghost Rails

Just beneath the surface of the modern city lie the remnants of its expansive early 20th-century streetcar system.

July 13, 2025 - WTTV

Blue and silver Amtrak train with vibrant green and yellow foliage in background.

Amtrak Cutting Jobs, Funding to High-Speed Rail

The agency plans to cut 10 percent of its workforce and has confirmed it will not fund new high-speed rail projects.

July 14, 2025 - Smart Cities Dive

Worker in yellow safety vest and hard hat looks up at servers in data center.

Ohio Forces Data Centers to Prepay for Power

Utilities are calling on states to hold data center operators responsible for new energy demands to prevent leaving consumers on the hook for their bills.

July 18 - Inside Climate News

Former MARTA CEO Collie Greenwood standing in front of MARTA HQ with blurred MARTA sign visible in background.

MARTA CEO Steps Down Amid Citizenship Concerns

MARTA’s board announced Thursday that its chief, who is from Canada, is resigning due to questions about his immigration status.

July 18 - WABE

Rendering of proposed protected bikeway in Santa Clara, California.

Silicon Valley ‘Bike Superhighway’ Awarded $14M State Grant

A Caltrans grant brings the 10-mile Central Bikeway project connecting Santa Clara and East San Jose closer to fruition.

July 17 - San José Spotlight