SAN DIEGO — If you’ve driven in California long, you know the speed limit on most freeways is set at 65 miles per hour — how much faster you drive is a matter of personal risk, legal and otherwise.

In dozens of other states, 70 mph speed limits are more common, with eight states that routinely push it to 80 mph.

So who’s responsible for setting the speed rules? While speed limits in your neighborhood are managed by the city or another local government entity, freeways fall to state lawmakers and the California Department of Transportation, better known as Caltrans.

The California legislature is responsible for the general guidelines for speeds on different types of roads, like rural highways or city freeways. The policies agreed on by lawmakers are then laid out in the state vehicle code.

While that sets the template for maximum speed limits (55 mph on undivided two-lane roads, 65 mph on all others), posted speeds can vary in practice. Caltrans’ California Manual for Setting Speed Limits lays out the process in detail. In short, studies by traffic engineers can result in minor deviations.

In some cases, that can bump the limit up to 70 mph, like on a well-known stretch of Interstate 15 in northern San Diego County, for example. In other areas, the speed limit might be reduced slightly.

The Insurance Institute for Highway Safety, a nonprofit funded by auto insurance companies, provides regular comparisons of maximum posted speed limits nationwide. The institute is one of the industry’s foremost sources for crash research and vehicle safety ratings.

Here’s how California stacks up — you’ll notice, our upper limit tends to be a bit lower than other states. And check out the speed demons in Nevada, Montana and South Dakota.

StateRural interstatesUrban interstates
Arkansas75; trucks: 7065
California70; trucks: 5565; trucks: 55
Idaho75; 80 on specified segments of road trucks: 7075; 80 on specified segments of road; trucks: 65
Indiana70;trucks: 6555
Kentucky65; 70 on specified segments of road65
Michigan70 (65 trucks); 75 (65 trucks) on specified segments of road70
Montana80; trucks: 7065
New Hampshire65; 70 on specified segments of road65
New Jersey6555
New Mexico7575
New York6565
North Carolina7070
North Dakota7575
Oklahoma75; 80 on specified segments of road70
Oregon65; 70 on specified segments of roadtrucks: 55; 65 on specified segments of road55
Rhode Island6555
South Carolina7070
South Dakota8080
Texas75; 80 or 85 on specified segments of road75
Utah75; 80 on specified segments of road65
Washington70; 75 on specified segments of road; trucks: 6060
West Virginia7055
Wyoming75; 80 on specified segments of road75; 80 on specified segments of road
Data courtesy of the Insurance Institute for Highway Safety.

You can view the list with footnotes and find additional information here.

Safety first

While California’s upper speed limits appear to be a little more tame than elsewhere in the country, researchers with the insurance institute and AAA argue they shouldn’t budge higher.

A study by the two organizations found that even small increases in speed can have “huge effects on crash outcomes,” the authors wrote. Researchers conducted crash tests at three different rates (40, 50 and 56 mph) and found that only slightly higher speeds resulted in greater risk of severe injury or death.

“Higher speed limits cancel out the benefits of vehicle safety improvements like airbags and improved structural designs,” said Dr. David Harkey, the insurance institute’s president, in a statement accompanying the study.

“The faster a driver is going before a crash, the less likely it is that they’ll be able to get down to a survivable speed even if they have a chance to brake before impact.”