Cornerstone empirical briefs built directly from reconciled California Highway Patrol CCRS / SWITRS collision snapshots and Caltrans corridor records. Every brief publishes exact observation dates, raw numerators and denominators, coordinate-coverage limits, and a reusable citation.
In a 365-day California Highway Patrol CCRS window across 32 state highways, I-5 and US-101 lead raw collision counts, while two-lane mountain and desert routes carry more than triple the severe-injury share and urban ramp terminals concentrate neighborhood harm.
Statewide, roughly one in twelve reported California crashes involves a pedestrian, bicyclist, or motorcyclist (8.40% in the latest 90-day Pulse; 8.6% across 371,698 crashes in the 365-day benchmark), yet local concentrations exceed twice that rate in coastal and high-arterial communities.
Across 74,533 reported California collisions in the 90-day Pulse window, afternoon commuter hours (15:00 to 17:00) produce over 5,300 crashes per hour at below-average severity (0.77x to 0.87x), whereas every hour from 20:00 through 03:00 exceeds 1.40x the statewide severe-injury baseline.
Public California collision files contain 2,631,409 collisions and 5,478,771 party records between 2020-01-01 and 2026-10-27, but unmapped rows, street-inferred coordinates, directional ramp aliases, and 93,955 fragmented vehicle labels will distort naive SQL queries unless audited explicitly.
Cross-check these statewide findings against individual city, ZIP, and vehicle profiles in Find Your Story, inspect all 32 highway corridors in Road Profiles, or download CSV packets in the Reports Library.