I have just returned from a 25 state, 33 day, 7700 mile road trip around the US. I Left from Denver, north to Jackson Hole, Wyoming, then along the Canadian Border through Montana, North Dakota, Minnesota finally to Wisconsin. I Had to get tires in Duluth (cansed by a lousy rear wheel alignment here in Denver), then south along the Great Lakes, eventually to Mamouth cave in Kentucky, via Illinois, Indiana, Ohio. I then headed north and east to West Virginia and Pennsylvania, New Jersey, Deleware and Maryland, spending Columbus Day weekend with my daughter and her husband. Next headed to Williamsburg Virginia for a professional meeting with my wife. After she flew back to Denver, I continued south along North Carolina's outer banks, across NC to the Blue ridge highway in Tennessee. I continued through north west Georgia, Alabama and Florida and the gulf coast. Back into Alabama, Mississippi and a few hours in New Orleans, Louisiana. (The weather reports were predicting a major snow storm back in Denver in four days.) For the heck of it I drove across Lake Ponchatrain (boring), into Arkansas, Oklahoma, Texas, New Mexico, and finally back in Colorado. At this time of the year there wasn't enough daylight to bother driving more than 10 or 11 hours in a day. Why take a signt seeing trip in the dark?
To answer the OP original question, several years ago I did a 14 - 15 hour stint from Illinois to Denver -- covering 1000 miles.
I am completing a journal of the trip and will post it soon.