Dash 8-200
Air Traffic Control Fully Certified
Confusion; Situational Awareness
ATC Issue All Types; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued New Clearance
Human Factors; Procedure
Air Carrier X filed and was issued IAD..COLNS..HVQ..CRW. Preferential route changed it to LDN.J134.COLNS.J6.HVQ. The change was thought to be the old route. The filed route was issued; but the preferential route was not suppressed. The Aircraft got airborne and the Departure Control thought Air Carrier X was issued the preferential route. I realized the error and called Departure Controller to let him know. No separation was lost. The Departure Controller fixed the issue in the air. Recommend following through with any changes that are made for issuing the clearance to the pilot and making any changes in the computer before going on to something else. Also; remember to use strip marking. Strip marking was forgotten here and it could have prevented the situation.
IAD Controller voiced concern regarding the 'lost art' of strip marking providing a recent example of same.