CHICAGO CRASH TABLES: METHODS AND DEFINITIONS
Source: City of Chicago Data Portal. Tables are the firm's own aggregations.
Published by TORKLAW. Data pulled October 11, 2026 (U.S. Central). 2026 figures are partial.

DATASETS
- Traffic Crashes - Crashes (dataset ID 85ca-t3if). Rows through 2026-10-11. Source of tables A1, A3, A4, A6, A8, A9, A11 and the "crashes" rows of A2.
- Traffic Crashes - Vision Zero Chicago Traffic Fatalities (dataset ID gzaz-isa6). Records from 2019-01-03 through 2026-07-29. Source of the "vision_zero" rows of A2.
The portal lists both datasets under "See Terms of Use". This file makes no license claim.

TABLES
A1 annual crash counts. A2 deaths by source. A3 injury crashes by weekday and hour. A4 injury crashes by month. A6 primary contributory causes in injury crashes. A8 pedestrian and pedalcyclist first-collision crashes. A9 lighting condition. A11 crashes with a fatal or incapacitating injury. data_dictionary.csv defines every column.

DEFINITIONS
- Crash with any injury: injuries_total > 0. This includes possible injuries that were reported but not evident at the scene.
- Crash with a fatal injury: injuries_fatal > 0. Fatal injuries: the sum of injuries_fatal.
- Crash with a fatal or incapacitating injury: injuries_fatal > 0 OR injuries_incapacitating > 0.
- Rows with no injury figure are not counted as injury crashes and are not set to zero. The count of such rows is shown in the tables.
- Pedestrian and pedalcyclist crashes use the first type of collision recorded. They do not count every crash that involved a person walking or biking.
- Darkness: lighting condition "DARKNESS" or "DARKNESS, LIGHTED ROAD".
- Primary cause: the officer-coded primary contributory cause. It is not a finding of fault. "Unable to determine" and "not applicable" are shown separately.
- Hit-and-run, police-district and block tables are not published here.
- Shares are exact fractions with their denominators; no value is rounded in the tables.

LIMITS
- The crash records come from Chicago Police Department reports on city streets. Most interstate and expressway-ramp crashes are not included. About half of reports are written by drivers at a police district; the rest by officers at the scene.
- Citywide coverage in the data begins in September 2017. Reports are added when finalized, so recent months are incomplete and older records can change.
- The Vision Zero fatality file follows the city's own review and inclusion rules, is updated monthly, and has missing and repeated person IDs. Its rows were counted as published, with none removed. Its totals differ from the crash records. No claim is made about which is "correct".
- The tables use no traffic-volume, population or exposure data. They do not show risk per trip, per mile or per person, and they do not explain why counts change.
- Counts are for these data snapshots only and can differ in later pulls.
