A year after marijuana sales became legal in Colorado, the impact on tourism is difficult to assess.

At least 18 companies offer bus tours of marijuana facilities, and a Denver bed and breakfast markets itself as a "bud and breakfast," the Denver Post reported Sunday (http://tinyurl.com/mawym96).

But state-funded agencies aren't promoting marijuana tourism, and no statistics are available on its impact.

Colorado Tourism Office Director Al White said promoting pot-oriented travel could put the state in danger of violating laws. Marijuana is still illegal under federal statutes.

White also questioned the potential of the market.

"If you've been smoking pot all your adult life in Columbus, Ohio, and you buy it from the guy on the corner, I really don't think you're going to feel a need to go and buy it in Colorado," he said.

Richard Scharf, CEO of Visit Denver, the city convention and visitors bureau, said the market for marijuana tourism is tiny compared to Colorado's overall travel industry.

"We just don't have any research at all that says (marijuana) is driving demand," he said. "When you have 14 million annual visitors, we just don't see pot as a significant driver in that market."

JJ Walker said his Denver business, My 420 Tours, had a good first year, providing marijuana tours to between 4,000 and 5,000 customers since recreational cannabis sales began Jan. 1.

"We get the 60-year-old business executive who comes here to do something different, and we get the 28-year-old who just wants to have fun," Walker said.