It is 543.74 miles according to MapQuest.
It is 544 miles to Oklahoma City.
My guess is Oklahoma City because Dallas is farther and i think Denver and Albuquerque may even be closer to Amarillo then Dallas is.
It is 544 miles according to MapQuest.
It is an 8 hour drive.
8 hours 26 minutes.
It is 543 miles according to Google Maps.
544.
Albuquerque, NM..
It is 543.73 miles according to MapQuest.
That would be Albuquerque, New Mexico which is 544 miles from Oklahoma City and the true halfway point would only be 503.5 miles.
About 950 miles depending on the route taken to Albuquerque.
MapQuest estmates the driving time as 8 hours and 1 minute.