Dion, a junior from Pewaukee, was with friends about the time the bars closed, said police Sgt. Roger Barnes. Dion's friends turned to get on a bus back to campus, but when they turned around Dion was gone.
Police say they've labeled the case a "possible missing person" because family and friends say it's out of character for him to be out of touch for this long.
They say no foul play is suspected at this point.
Dion is described as 5'9", 165 lbs., with brown hair and hazel eyes. At the time of his disappearance he was wearing blue jeans and a brown long-sleeved T-shirt.
The La Crosse Police telephone number is (608) 785-5962.