Per the SPC Database, 15 tornadoes touched down in the state of Nebraska on March 13, 1990. The strongest, an F4 traveled from 3 miles south of Red Cloud in Webster County and lifted 3 miles East of Schuyler in Colfax County. The max width was 440 yards. There were 8 reported injuries.
The SPC has a path length of 131 miles making it the longest path for the March 13.
A couple of discrepancies on the path: The Storm Data entry and the summary from the NWS both state the path was 124 miles. Still qualifies as the longest path for the day.
Thomas Grazulis states in his book Significant Tornadoes that this was a family of tornadoes that covered 124 miles.
Although there was damage along the entire path, some of the worst damage was in Nuckolls County and the town of Lawrence.
Grazulis, Thomas P. (1993). Significant Tornadoes 1680-1991: A Chronology and Analysis of Events. St. Johnsbury, VT: The Tornado Project of Environmental Films. Page 1294.