The police department in Portland, Oregon, is now offering people advice on where to buy marijuana. Seriously:

If you are looking to buy marijuana, go to a legit businesses and avoid street dealers who might rob you. #ItsLegal pic.twitter.com/kLmHNAXjS2 — Portland Police (@PortlandPolice) June 11, 2016

Sure, this is by and large just a silly tweet. But it shows just how far marijuana legalization has come over the years — to the point that a major police department, the agency that used to enforce the prohibition of marijuana, is now giving tips on where to buy it.

Imagining something like this would have been tough just a few years ago. In 2005, just 36 percent of Americans supported full legalization, according to Gallup surveys. And in 2010, California, the first state to truly legalize medical marijuana, rejected a marijuana legalization ballot measure.

Within just a few years, the political climate has completely changed. In 2015, support for legalizing marijuana hit 58 percent. Four states (Colorado, Washington, Oregon, and Alaska) and Washington, DC, have legalized the possession of marijuana, with the four states also legalizing pot’s sale for recreational purposes. And at least five other states, including California, are expected to vote on whether to legalize in November. Whereas legalization supporters were largely dispirited just a few years back, they now regularly refer to federal legalization as “inevitable” and “a matter of time.”

When a big city’s police department is tweeting about where to buy marijuana legally, it's easy to see why advocates are now so confident. It’s a remarkable shift.

Watch: How medical marijuana could help fight the opioid painkiller and heroin epidemic