Illinois State Route 13 is in Washington County for less than one mile. Only the westbound lane of IL St Rt 13 is. IL St Rt 13 does not pass through any town in Washington County IL St Rt 13 multi-plexes in washington County Illinois State Route 4, near Tilton. IL St Rt 13 does not intersect any route in Washington County.
NB IL St Rt 4/WB IL St Rt 13 in its short passage through Washington County. The lane on the right, from the curve to the bridge is Washington County. The left lane from the bridge and around the curve is in St. Clair County.
