The 1990 Interstate 75 fog disaster was a traffic collision that occurred on the morning of December 11, 1990, on a section of Interstate 75 (I-75) near Calhoun, Tennessee, during dense fog which obscured the visibility of motorists. The collisions occurred in an area where fog is common and had been the site of previous multi-vehicle collisions caused by poor visibility. It consisted of a series of multi-vehicle collisions that ultimately involved 99 vehicles, and resulted in 12 deaths and 42 injuries. It was reportedly the largest motor vehicle collision in United States history when it occurred, in terms of the number of vehicles, and was the largest and second deadliest vehicle accident in Tennessee history behind the 1972 Bean Station bus-truck collision, which killed 14. The disaster resulted in multiple safety improvements to the section of I-75 where the collision occurred.

Interstate 75 (I-75) in the US state of Tennessee runs from Chattanooga to Jellico by way of Knoxville. I-75 enters the East Tennessee region from Georgia, following the Tennessee Valley all the way through Knoxville to near Rocky Top, then climbs into the Cumberland Mountains before crossing over into Kentucky at Jellico.