One problem I see with the map is it doesn’t show any traffic from Southern California along I-10/I-20 corridor to the east coast. I drive it every now and then from DFW to Phoenix and back and can tell you it’s solid 18 wheelers both ways. And, if your not willing to run 80~85 mph better drive on the service road....
I suspect a lot of that truck traffic is moving imports from the Ports of LA and Long Beach. That’s a lot of freight, but I’ll bet hardly any of it involves food products.