Driving from St. Louis to Salt Lake City . . . in March.
 

My husband and I need to get to Salt Lake City, UT (and back) during the third week in March. Thus far, flying is very cost prohibitive, so we're thinking about driving.

I love road trips, and if it were summer time, I would be thrilled to take either I-70 or I-80 (although I hear the latter is pretty boring). But we have to go in March, so we're pretty concerned about the weather in both Colorado and Wyoming.

Although it adds about 5-6 hours, we're also toying with the idea of going down through Oklahoma to Albuquerque and then north into Utah.

Is there a better route we should consider? I would love any insights and tips you have to share!

There is no guarantee that the I-40 route will be an improvement.

I think the main thing you need to do is leave early enough that you can sit out a storm in a hotel somewhere until they get the roads plowed. They do a good job of this in Colorado since the ski industry depends on people being able to get to the resorts.

Check the airfare to Las Vegas. It may be cheap enough to get a rental car there and drive up I-15.

It is not a difficult drive on I70. You can easily reach Denver the first day. just stay tuned to the weather. Colorado really does a good job with road maintenance. Kansas, maybe. I had to stop one time in Goodland because the roads were so icy--slid off the road twice!! The next day, the roads in Colorado--about an hour--were well cleared.

I'd opt for I-70 route. Having drive all three several times, it is easily the most scenic. As the above posters noted the state does a good job of keeping the major roads oepn. It would be a good idea to allow enough time, as suggested, that if you have to sit out a day while a major storm passes through you can still make your destination.
For a variation on the return trip you could drop down I-15 to Las Vegas then US 93 via Hoover Dam Bridge into Kingman, AZ (Kingman to Amarillo is probably the most scenic part of that trip)then take I-40 as far as Memphis before turning north on I-55.

Thanks so much for the input! It's good to know that roads typically get cleared quickly. We would have a time cushion both going and coming, so taking I-70 is sounding better and better all the time!

I-70 is your best choice and they break off at Green River and head north to SLC. As Gretchen pointed out if you have problems in Colorado it will be around the Kansas/Colorado border and not the mountains. In the mountains the snow just falls but in the flat lands of western Kansas and eastern Colorado the wind blows and the drifts are the problems.

And, of course, you would be wise to have access to an extra blanket, warm clothing, some water, and granola bars in your car just in case unexpected problems arise. I-70 is rarely closed more than three or four times a year so the probability of it being closed is very low.

Thanks, fmpden, that's helpful! In addition to the items you suggested, I'm thinking we'll take our winter rated sleeping bags since we'll have the trunk space.