When the Camp Fire tore through Paradise, California in 2018, 66 of the town's 86 wildfire deaths happened in a single place—a community with six outward roads that descended into gridlock as residents fled an unstoppable wall of flame. A new study published in the Proceedings of the National Academy of Sciences has uncovered why that number matters so much: six exits is not a coincidence, but a critical threshold that separates communities where people can escape from those where they cannot.
Researchers at UC Santa Barbara's National Center for Ecological Analysis and Synthesis compiled the most extensive database of wildfire fatalities ever assembled, covering 342 deaths across the United States from 2008 to 2024. What they found is both precise and alarming. Fatalities drop sharply as communities gain more outward road access—but only up to about six exits. Beyond that point, additional roads offer little further protection. The threshold held steady regardless of geography or town size, suggesting something deeper than demographics: it is a structural constraint. Road redundancy is what saves lives.
The pattern echoes through America's deadliest fires. In 2023, Lahaina, Hawai'i lost 102 people—a town with just four exit routes. Berry Creek, California, with only two exits, saw 13 deaths during the 2020 North Complex Fire. The data reveals a national emergency hidden in plain sight. When researchers combined egress data for every U.S. community under 50,000 residents with wildfire hazard maps and census figures, the numbers became stark: 17.7 million Americans live in communities below the critical six-exit threshold. Of those, 2.5 million face high wildfire hazard. And 528 communities have no major road exits at all, scattered across 41 states.
The risk is not confined to California or the West. Dangerous combinations of limited roads and high fire risk exist in Oklahoma, Florida, and Hawai'i—states often overlooked in national wildfire policy. As climate change expands the geography of fire hazard, that blind spot will grow more costly. "Seventeen million Americans are living in communities that, by this measure, are not designed to survive a fast-moving wildfire," said Max A. Moritz, UC Cooperative Extension Wildfire Specialist for California. "That should be a wake-up call—not just for California, but for every state that thinks wildfire isn't their problem yet."
The researchers are realistic about solutions. Building new roads is not always possible—steep terrain, ecological constraints, and cost make it impractical in many places. Instead, they propose three complementary approaches: expanding egress infrastructure where feasible, improving early warning systems and evacuation behavior, and investing in pre-planned shelter-in-place options like temporary refuge areas for when evacuation fails. The team has made their risk maps publicly available, designed to help planners and policymakers identify where to prioritize action first. This work is part of the Wildfire Resilience Index, a project dedicated to building data-driven tools that help communities understand and build resilience against a threat that no longer belongs to one region alone.