Found this forum thanks to Google. Very neat place.

Anyway, I was searching for best route from Springfield, Missouri to Fremont, CA in August. Will be using smaller U-Haul box truck to move my son's stuff to an apt. I can't decide whether to use I-80 or I-40, would prefer a route with less truck traffic. I did see a mention about avoiding CA-58 to Bakersfield. South route probably will be pretty hot.

Welcome to Fodors!

I've never driven I-80, but I have done I-40 a couple of times. It seems to be a bit shorter, both in miles and hours. There seem to be more towns along the route for stopping to sleep and any emergency that could occur with the U-Haul. Is your son moving for school? It's a pretty easy drive, but there are trucks. I don't know if you can avoid them anywhere. Plenty of gas stations too. Once you leave Arizona, there will be fewer services because you'll be in the desert in California where it will be HOT. Just make sure you top up the gas tank and have plenty water to drink. It's a well-traveled route, you'll be fine. I'm assuming the truck will have ac.

The I-40 route is shorter (time and miles). It is quite a mountain to go over the Tehachapi Pass between Barstow and Bakersfield. Unless you are overloaded, the engine and brakes should get you there safely. Plan on 29-30 hours with wheels turning to cover that distance. Instead of crossing over to I-5 at Wasco, you could continue north on 99 to Chowchilla and then take 152 west. Gas prices are crazy in California so plan on filling up in Arizona.

It looks like both routes will have some altitude gain somewhere along the way which would be one of my main considerations.

According to google the highest point on I-80 west of the Mississippi is in Wyoming,"I-80 reaches its maximum elevation of 8,640 feet (2,630 m) above sea level at Sherman Summit, near Buford, which, at 8,000 feet (2,400 m), is the highest community on I-80".

For I-40 It reaches its highest point in the state of 7,275 feet (2,217 m) at the Continental Divide in western New Mexico between Gallup and Grants.

You might want to consult Via Michelin route planner for both routes since it can help calculate total gas prices. And also gas buddy for gas prices. For me, both gas prices and elevation gain would be the top two considerations driving a UHaul truck. I would definitely eliminate I-70 since the elevation inwestern Colorado and reaches 11,158 feet! I remember driving a lightly loaded new Toyota Corolla on that route and having to chug chug to the top lol!

gasbuddy.com

https://www.viamichelin.com/web/Routes

I totally agree that taking 99 to Chowchilla and then take 152 to rejoin I-5 is the route to go if you take I-40. They have improved 99 greatly over the years, much of it three lane now, and there is much less end-to-end stretches of semis on that route versus I-5. And nicer places to stop for meals, etc. We drive the Tehachapi stretch every year driving from the NW to Palm Springs and it is a very scenic nice drive. As tomfuller mentions, there is an altitude gain there-here is that info if you are interested. While it is high it isn't as high as the altitudes in NM above:

Elevation of Tehachapi is 3969.74 feet or 1209.98 meters and the elevation of Barstow is 2235.1 feet or 681.26 meters, which is a difference of 1734.64 feet.

Thanks for the replies. They are very helpful.

We take lot of road trips but have not been on I-80 west of Rock Springs, Wyoming and west of Flagstaff, Arizona on I-40. As we're flexible on the routes and will be watching weather and road conditions before deciding. After your comments, I looked at CA-99 and that looks like a good route to use.

High gas prices won't be fun though. Ha.