When we think about violent crime, we often imagine dark alleys, abandoned buildings, or entire 'bad neighborhoods.' But decades of crime mapping research reveals something surprising: violence isn't randomly distributed across dangerous areas. Instead, it clusters in incredibly specific locations—often just a handful of addresses in any given city.

This concentration is so extreme that criminologists have a name for it: the law of crime concentration. In city after city, researchers find that roughly 5% of addresses generate 50% of all violent crime calls. Understanding why certain places become violence magnets—and what makes them different from seemingly identical locations just blocks away—offers powerful insights for prevention that go far beyond traditional policing.

Minneapolis criminologist Lawrence Sherman first discovered this pattern in the 1980s when analyzing 323,000 police calls. Just 3% of addresses produced 50% of all calls for service. This wasn't a fluke—the same pattern appeared in Boston, Seattle, Sacramento, and dozens of other cities worldwide. Even more striking: these hot spots remain remarkably stable over time, with the same addresses generating problems year after year.

What makes these locations special? Research by David Weisburd found it's not poverty or demographics—it's specific environmental features. Hot spots typically combine multiple risk factors: poor lighting, limited natural surveillance from windows, escape routes for offenders, and activities that bring together motivated offenders and suitable targets. A corner with a liquor store, check-cashing business, and bus stop creates what researchers call a 'crime generator'—drawing people together in ways that increase conflict opportunities.

The concentration is even more extreme for violent crimes. In Boston, just 5% of street corners and block faces accounted for 74% of shootings over a 29-year period. These weren't entire neighborhoods but specific intersections, often just feet away from peaceful areas. One block might see multiple shootings yearly while the adjacent block remains violence-free for decades. This micro-geographic pattern suggests that violence isn't about 'bad areas' but about very specific problematic places.

Not all bars are created equal when it comes to violence. Research shows that in any city, about 5% of bars generate 50% of all bar-related violence. These 'risky facilities' share common features: they serve intoxicated patrons, have inadequate security, tolerate drug dealing, feature aggressive bouncers, or create bottlenecks where conflicts escalate. One study in Newark found that simply having bars switch from glass bottles to plastic cups reduced violent injuries by 38%.

Convenience stores show similar patterns. Those that become violence hot spots typically cash checks, sell single cigarettes, allow loitering, have poor sight lines from the register, or employ staff who can't or won't intervene in disputes. In Philadelphia, researchers found that convenience stores with bulletproof glass actually experienced more violence—the barriers prevented staff from building relationships with customers and intervening early in conflicts.

Transit stops represent another category of risky facilities. Violence concentrates at specific bus stops and subway stations that combine poor design with inadequate management. Features like hidden corners, broken lighting, and isolated waiting areas create opportunities for robbery and assault. But simple changes make huge differences: Washington DC's Metro reduced violent crime by 26% simply by removing newspaper boxes that blocked sight lines and adding classical music at problem stations.

Every location has what criminologists call 'place managers'—people who control specific spaces and regulate behavior there. Effective place managers range from store owners and security guards to apartment superintendents and even regular customers. Research consistently shows that violence drops dramatically when these informal guardians take ownership of spaces. The absence of engaged place management, more than poverty or demographics, predicts which locations become violent.

Consider two identical apartment complexes in Cincinnati studied by John Eck. One experienced constant violence; the other remained peaceful. The difference? The peaceful complex had an engaged landlord who screened tenants, quickly fixed broken windows and lights, enforced guest policies, and evicted problem tenants. The violent complex had an absentee owner who collected rent but ignored disorder. When new ownership implemented basic place management, violence dropped 66% within a year.

The most effective violence prevention often involves strengthening place management rather than increasing arrests. In Jacksonville, police worked with owners of problem motels to implement guest registration, install better lighting, remove room doors that faced parking lots, and hire security during peak hours. Violence dropped 84% without displacing crime to nearby motels. Similarly, problem bars that agreed to server training, security cameras, and capacity limits saw violence decrease by an average of 42%, while bars that refused interventions continued generating violence.

The concentration of violence in specific places challenges our assumptions about crime. It's not about 'bad neighborhoods' filled with dangerous people—it's about particular locations where environmental factors, absent guardianship, and poor management create opportunities for violence. This pattern, consistent across hundreds of cities, suggests that violence is more preventable than we often assume.

By focusing on the handful of addresses that generate most violence, strengthening place management at risky facilities, and making small but crucial environmental changes, communities can achieve substantial violence reductions. The geography of violence isn't destiny—it's a map showing exactly where prevention efforts will have the greatest impact.