Guides

Reading a fatal crash rate, one question at a time

Each guide explains one thing about fatal crash rates in plain words, with a worked example on a real county or state. The figures come from the same NHTSA, Census and FHWA files as the pages, and every guide says what it does not cover.

What Does a Fatal Crash Rate per 100,000 Mean?

A fatal crash rate per 100,000 is NHTSA fatal crashes divided by Census population, times 100,000. The math on a real county, and why small counties swing.

Read guide →Fatal Crashes per 100 Million Vehicle-Miles, Explained

The per-mile fatal crash rate divides NHTSA fatal crashes by FHWA vehicle-miles. How it differs from the per-person rate, worked on one state, and why counties have none.

Read guide →What Counts as a Fatal Crash in FARS?

NHTSA's FARS records a crash when someone dies within 30 days on a public road. What that includes, what it leaves out, and why crashes and deaths are two numbers.

Read guide →