States › Colorado › Routes › State Route 121
State Route 121
Fatal crashes 2015–2024 62Deaths 64Counties 3Latest data year 2024
FARS data are based on police crash reports and other sources; the drunk-driving measure is based on the highest BAC of any driver in the crash. Latest data year: 2024. The route is the trafficway recorded for each crash (FARS TWAY_ID); the same route number in another state has its own page.
State Route 121 in Colorado was the trafficway in 62 fatal crashes between 2015 and 2024, in which 64 people died.
That is 1% of the 6,017 fatal crashes in Colorado over the same years. The ten-year crash count rose 63% from 38 in 2005–2014 to 62 in 2015–2024.
The crashes were concentrated in Jefferson County (56), Broomfield County (4) and Denver County (2).
33.9% of the crashes had a driver reported as drinking (Colorado: 34.1%) and 35.5% had a speeding-related driver (35.4%); pedestrians were 26.6% and motorcyclists 23.4% of those killed.
Fatal crashes per year
Route identification in FARS is consistent from 2000; earlier years are not shown. Shaded band: the ten-year window used for the shares below.
Compared with all fatal crashes in Colorado
| Measure | State Route 121 | Colorado |
|---|---|---|
| Fatal crashes, 2015–2024 | 62 | 6,017 |
| Deaths, 2015–2024 | 64 | 6,518 |
| Deaths per fatal crash | 1.0 | 1.1 |
| Share of state fatal crashes | 1% | 100% |
| Change vs previous ten years | +63% | +31% |
Factor shares
Counties along the route
| # | County | Fatal crashes on SR-121 | Share of route | County total, all roads |
|---|---|---|---|---|
| 1 | Jefferson County | 56 | 90% | 450 |
| 2 | Broomfield County | 4 | 6% | 34 |
| 3 | Denver County | 2 | 3% | 581 |
Hour of day
Share of fatal crashes on State Route 121 beginning in each hour, 2015–2024; tick marks the Colorado share for all roads.
Where along the route
| Mile marker range | Fatal crashes | Share |
|---|---|---|
| Mile 10–15 | 23 | 37% |
| Mile 20–25 | 13 | 21% |
| Mile 0–5 | 8 | 13% |
| Mile 5–10 | 7 | 11% |
| Mile 15–20 | 7 | 11% |
| Mile 25–30 | 4 | 6% |
Five-mile bins by FARS milepoint, the six with the most fatal crashes; 100% of crashes on the route have a milepoint. Milepoints are as recorded by the state and can restart at county or district lines.
Other routes in Colorado
- Interstate 25 382
- Interstate 70 313
- US Route 287 177
- US Route 40 176
- US Route 50 169
- US Route 85 146
- US Route 160 136
- Interstate 76 130
- US Route 24 110
- US Route 6 109
- US Route 34 104
- US Route 285 103
All routes and counties in Colorado
Questions and answers
How many fatal crashes have there been on State Route 121 in Colorado?
62 fatal crashes with 64 deaths over 2015–2024, per NHTSA's FARS. The route is the trafficway recorded for the crash; the same numbered route in another state has its own page.
Which counties along State Route 121 had the most fatal crashes?
Jefferson County (56), Broomfield County (4) and Denver County (2).
What share of crashes on State Route 121 involved alcohol or speeding?
33.9% had a driver reported as drinking and 35.5% a speeding-related driver, against 34.1% and 35.4% for all fatal crashes in Colorado.
When do fatal crashes happen on State Route 121?
58.1% of the crashes were between 6pm and 6am. The hour chart on this page shows the full distribution.
Provenance
Source: NHTSA Fatality Analysis Reporting System, annual national CSV files 2000–2024 (accident, vehicle and person tables), public domain. Route pages are built for signed Interstate, US and state routes with at least 20 fatal crashes in 2015–2024. Data through 31 Dec 2024; generated 30 Sep 2026. See methodology and corrections.