L.A.'s notorious 405 Thanksgiving traffic jam is built on a myth. Here's what the data show
When the sun sets Wednesday night, L.A.'s attention will briefly turn as it does every Thanksgiving Eve to the 405 Freeway.
TV news helicopters will hover overhead, reminding the world that there is perhaps no worse traffic than on the 405.
For more than a decade, photos and videos of the epic gridlock stretching from Los Angeles International Airport into the Westside have signaled the unofficial start of the holiday weekend and a bit of poetic justice for snowbound East Coasters jealous of our warm Thanksgiving al fresco.
But Caltrans traffic data reviewed by The Times show that Wednesday evening is not when the worst traffic occurs.
Although speeds are well below average on Thanksgiving Eve, Tuesday is actually the worst traffic day on that stretch of freeway, a Times analysis of Caltrans data shows. And the data reveal that even Monday is a bit worse than Wednesday.
The chart below plots average speeds on Los Angeles County's stretch of the 405 in both directions during the last five Thanksgiving weeks.
Though overall traffic was worst in 2019 before improving in 2020 due to the pandemic, speeds have been well below average — 53.7 mph last year on the 405 — every Tuesday and Wednesday before Thanksgiving in the last five years.
The Tuesday-Wednesday crush happens nationwide, said Marie Montgomery, spokesperson for the Auto Club of Southern California, "and then coming back into town Sunday afternoon and evening can be busy as well."
Though Thanksgiving Eve has been bad for the 20 years she has tracked traffic, "it did start to move more and more into Tuesday," she said.
As Wednesday traffic worsened, "people tried to get a jump ahead of the holiday," she reasoned.
Because of lighter commute traffic as people take time off work and schools close, mornings present an opportunity to beat the rush, Montgomery said.
The Times analysis of the 405 shows that the Tuesday before Thanksgiving in 2019 was the worst day on record: Cars averaged just 41.3 mph throughout the day.
Read more: How 405 Freeway gridlock became the iconic image of an L.A. Thanksgiving
Last year, the speed was higher, about 48 mph on Tuesday and 49 mph Wednesday.
A closer look at the data reveals that the evening rush hour on those two days was the worst time to drive the 405, and it's a safe bet that it will be again this year.
During the Thanksgiving week of 2023, the morning traffic peak — about 8 a.m. — was equally bad Monday, Tuesday and Wednesday before dropping off Thursday and Friday.
However, the peak was noticeably worse Tuesday than other days: Cars crawled along at just 34 mph from 5 to 6 p.m.
"Caltrans advises motorists to be extra cautious as a record number of Southern California residents are expected to travel for the Thanksgiving holiday," the agency said in a statement.
In the Southland, the Automobile Club of Southern California expects a record 6.6 million travelers, a 2.8% increase from last year. About 5.7 million are expected to travel by car, with Caltrans warning of possible wet weather on the horizon to make roads slower and more dangerous.
Those in L.A. County who must drive this week would do well to drive at off-peak hours or wait until Thursday. However, family members may be willing to suffer through the apocalyptic 405 to celebrate, if past data are any indication.
Times staff writer Shelby Grad contributed to this report.
This story originally appeared in Los Angeles Times.
