For those with a recent Android smartphone...
Turn phone one and say "Ok Google"
Then say "Show me Walmarts near me" or "Show me Walmarts near Denver Colorado"... or where ever
You'll get a map of the area, showing where Walmarts are located along with their phone numbers. Click and you can navigate directly to them.
Oh, you can replace "Walmart" with "Cracker Barrel", "Flying J", or even
"Truck stops".
While I usually do this on my Galaxy S5 smartphone (not when driving), we also have a $50 android tablet (Digiland 7" at BestBuy) that has built-in GPS. It links with the WiFi hotspot in my Verizon Android phone. Then my wife can give verbal commands to the tablet which gives the same information.
Hope this helps!