In October, according to proponents of the referendum , he’ll barnstorm the state to sell residents on Question 4, which would legalize the use and sale of marijuana for adults 21 and older.

And now public television personality and best-selling travel author Rick Steves has a new, more unlikely high-flying adventure: Selling Massachusetts voters on legalizing pot.

He’s taken viewers to the most beautiful sights in old Milan . Ridden a white steed through the rolling green hills of the United Kingdom. And toured the Zugspitze , Germany’s tallest peak.

Steves has a history of involvement in pro-marijuana efforts, so his advocacy for the question is not a shock. (He has praised the virtues of weed as a tool to travel vicariously, according to the New York Times Magazine — “You can read National Geographic about an ascent of Mount Everest, and that’s kind of exciting, but if you have a little help, you’re almost there.”)


But it still may surprise public television viewers to see their soft-spoken guide to Europe arguing for pot shops to take root Pittsfield to Provincetown.

Advocates say legalization would quickly begin to phase out the black market; would end more than a century of failed prohibition that has ensnared otherwise law-abiding citizens in the criminal justice system; divert money from criminal syndicates to companies operating on the up and up; fill the state’s coffers with new tax dollars; and improve the health and safety of children by moving marijuana sales from the street to licensed stores that check IDs.

Opponents say legalizing marijuana would lead to myriad problems, including more young people using the drug, in a state already struggling with a scourge of opioid use.

Joshua Miller can be reached at joshua.miller@globe.com.