Missouri 190's eastern endpoint is in Chillicothe at US 65. Actually, this is the southernmost eastern endpoint of the route. Missouri 190 starts in Grundy County near Edinburg and wends its way south and westward through Daviess County before making a sharp turn to the east at Lock Springs and heading into Livingston County.
This route was once designated as Missouri 170. Then Interstate 170 was designated in the St. Louis area. Missouri 170 was re-numbered to avoid duplicating the same number of the route.