Studies show that I-5 and I-10 in Southern California are near the top of the list each year for deadly accidents. These interstates carry the most traffic each day, and it’s not hard to believe they would present the most accident dangers to motorists.
State and U.S. highways may see lower traffic levels, but roads like Route 99 and U.S. 101 still get very busy and spawn terrifying crashes and fatalities. There may be more accidents on stretches through Los Angeles or San Francisco, but these routes, along with I-5, run for the most miles and always carry a high risk.
For a study of the latest 2025 accident statistics, Maison Law decided to focus on some of the iconic roadways that form the backbone of travel across our state. We focused on Highway 101, Highway 99, and I-5 to better inform drivers on the life-threatening dangers they face in big cities and across less-populated areas.
Where California’s Highways Rank Nationally
According to a study cited in the Sacramento Bee, I-10 through Los Angeles County and beyond is perhaps the deadliest route in California. It’s also nationally recognized for the life-threatening dangers and ranked seventh on a national list of the routes with the most fatalities each year. The road averaged around 1.52 fatal crashes per mile over three years.
I-80 in the Bay Area is another route to avoid if possible. It earned the discouraging rank of the 8th deadliest stretch of road in the nation. I-15 through Southern California and all the way to the Nevada state line also ranks high on the list.
The Dangers of Travel on Highway 99 in California in 2025
For our research, we focused on a smaller section of Route 99, but its whole length through California goes for 400 miles.
Our crash data calculated figures from the stretch of Highway 99 that runs from Kern County up through Sacramento County (almost 300 miles). This segment recorded 27 fatalities in 2025. That’s on top of 1,880 accidents involving injuries along that stretch of Highway 99 for the year.
These figures were documented by California’s Transportation Injury Mapping System (TIMS). Note: These are numbers just released in the spring of 2026, and they can, and likely will be updated throughout the year.
In the chart below, San Joaquin County and Sacramento County were the scenes of the most accidents. But they weren’t the most deadly counties for Highway 99 crashes. Kern County, with fewer accidents, actually recorded more fatalities (8). Merced County, reporting the least serious accidents on 99, still documented 7 tragic fatalities.
Fatalities Recorded on Highway 101 in California in 2025
Over roughly the same distance up and down California, Highway 101 accident totals tower over Route 99 statistics. Highway 101’s crash data for the year is, of course, boosted by its start in the traffic madness of Los Angeles.
And when San Diego accident numbers are removed from Interstate 5 accident data, this stretch of 101 actually saw many more serious accidents than the interstate saw over a similar number of miles.
Our data was taken from 2025 collision statistics for the stretch of Hwy 101 that starts in Los Angeles and runs up through San Francisco County, a trip of over 450 miles (the entire length of 101 is actually the longest road in California, spanning 808 miles in total). The segment we focused on saw 3,423 accidents involving injury and was the scene for 30 heartbreaking fatalities.
The Deadly Hazards of Travel on I-5 in California in 2025
The stretch of Interstate 5 extending from San Diego County all the way up through Sacramento County sees much more traffic than Highways 99 and 101, and many more tragic accidents. Interstate 5’s full run from the top to the bottom of California goes almost 800 miles, but we focused on a smaller section in Southern California and up the Central Valley (around 500 miles).
The stretch we pulled data on was the scene of at least 51 fatalities and 3,650 collisions involving injury in 2025, according to TIMS.
The extreme numbers are largely due to the routes through San Diego County and Los Angeles County. The freeway through these two counties accounted for around 70 percent of serious accidents along the stretch of Interstate 5 our researchers focused on. Both counties also accounted for 40% of the fatalities on I-5 over this specific segment in 2025.
Hope for a Safer 2027 on California Highways
There’s always the chance that these accident rates can drop from year to year. But it doesn’t magically happen.
It takes the commitment of California drivers to slow down, set down their cellphones, and pay more attention to the roads. This commitment could cut down on half or more of the accidents on our local freeways. It’s an investment in safety worth making.
If you are in a California car accident on any freeway or boulevard, and another driver caused your accident and injury, you may need a lawyer’s assistance to get fair treatment. If you suffer a serious injury, a lawyer is especially helpful. The higher the medical bills go, the harder insurance companies will make it for you to secure compensation for your economic and non-economic hardships.
To find out what’s possible, contact Maison Law to speak with a real California car accident lawyer about your case. There’s no obligation for your meeting, and your conversation is always confidential.
