Longest continuous road trip for me with no meal breaks was 20 hours but I only drove half of that. Eastern DC suburbs to Minneapolis. Left at 11 PM Eastern, arrived 6 PM Central (thus 7 PM Eastern) the next day. We would drive for 2 hours, take a short break, drive 2 hours more, take a slightly longer pit stop and switch drivers. Lather, rinse, repeat. We got caught in traffic because we went too close to Chicago. Oops.
Longest single-stretch solo drive was Fargo, ND, to eastern DC suburbs, which was a longer trip but involved meal breaks of over an hour, whereas the above drive had no break longer than 15 minutes.