Illinois Route 90Illinois Route 90 is an east-west state highway in northern Peoria [County, Illinois|Peoria County] in central Illinois. It runs from Illinois [Route 78|IL 78] north of Laura to IL 40 south of Edelstein. This is a distance of.Route descriptionIL 90 is an undivided two-lane surface road for its entire length. It passes north of the community of Monica and through the village of Princeville. While in Princeville, IL 90 runs concurrent with IL 91 from Princeville east for.HistorySBI Route 90 ran from Laura in Peoria County to Sparland in Marshall County along current Illinois 90, IL 17 and IL 40. This was changed to its current alignment in 1938.