Dylan Koshman's family has put up billboards like this one in Edmonton in four cities in Western Canada. (CBC)

A Saskatchewan family desperate for answers about their missing son is hoping billboards they've put up in four cities in Western Canada will generate tips.

Dylan Koshman, originally from Moose Jaw, vanished from his south Edmonton apartment on Oct. 11.

Koshman had been drinking and walked out the door after getting into an argument with a roommate, police said.

The 21-year-old hasn't been seen since.

"We're devastated by all this and we just want some answers," Koshman's mother Melanie Alix said in Moose Jaw Wednesday. "We just want to find Dylan."

The billboards feature a picture of the young man's face along with a number for Crime Stoppers.

"Thousands of people drive by these billboards a day," Alix said. "We want to get his face out there, and keep it out there until we get a tip or a lead."

Koshman's family has put up four billboards in Edmonton, Calgary, Saskatoon and Winnipeg.

The Pattison Group provided the space for the billboards and the family paid the printing costs.

The Edmonton police's missing persons unit is handling Koshman's disappearance, but has no involvement in the billboard campaign.

"We're in favour of anything that's going to keep the public's attention on this," Edmonton police spokesperson Jeff Wuite said Wednesday.

"We're still actively investigating this file, and as we stated from the beginning, Dylan Koshman had contacts not only here in Edmonton, but elsewhere as well. So to cast that net as wide as we can, or as wide as the family has, is certainly a good thing."

Koshman had been in Edmonton for about six months before his disappearance and had been working for an oil-and-gas contracting company.

His family travelled to Edmonton in October to knock on doors and put up posters in hopes of generating some leads.