I-40 is always crowded, I-70 ends at I-15 (typo! corrected)
Nationally, we need an I-50 and/or a I-60.
I-50 from Fresno California East to Las Vegas and on the North side of the Grand Canyon, to Page and then across to Ship Rock New Mexico to Raton New Mexico through the pan handle of Oklahoma to Tulsa to Bentonville Arkansas
This helps take alot of traffic off I-5, I-25, I-40 and I-80.
I-50 is a relatively snow free East West corridor for shipping / trucking and travel, connecting some of the faster growing areas of the country (Arizona to the South East)
I-60 from Bay Area through Yosemite to Tonopah NV to Cedar City Utah to Blanding Utah to Cortez Colorado to Pagosa Springs to Walsenberg Colorado to Witchta Kansas to SpringField Missouri ...
Again, takes traffic off I-80 (snow problems) and I-25.
It a problem that so much of East West traffic and shipping in the US is funnelled into I-40 and I-25. And some of the faster growing areas of the country are not currently served by a major East-West corridor.
I think this is "if you build it, they will come" kind of thing. If there were better East-West transit, those areas would grow, in the same way that lots of towns have grown along the I-40 Corridor and the I-80 Corridor.
Also, both I-50 and I-60 would provide great access to all the National Parks along the southern edge of the Colorado Plateau. Both could readily be called "The National Park Highway"