This history of ranch dressing is missing a sentence or two:
In 1997, Chicago-native Kelly McMahon started a new trend and simultaneously nearly bankrupted the Chili’s franchise in South Bend, Indiana: She requested ranch dressing with her complimentary nacho chips. Friends who sampled this concoction realized it was so good that there was no need to actually order real food. The idea caught on like wildfire with the rest of the Notre Dame student body and continues to this day.
(Link courtesy of Max, who is also a Certifiable Ranch Fiend.)