Law-abiding marijuana enthusiasts could find themselves in a bit of a predicament following voter approval of a recreational cannabis initiative in Missouri.

Though it soon will become legal for adults to possess and ingest cannabis, it could take a couple more months before they can legally buy it.

Maryland residents will have to wait even longer — until the middle of next year — before a recreational marijuana measure approved this past week can take effect.

With the addition of Maryland and Missouri, 21 states have legalized recreational marijuana for adults over the past decade — even though it remains illegal under federal law.

Marijuana advocates are pressing forward with similar efforts elsewhere, undeterred by defeats last week in Arkansas, North Dakota and South Dakota.

Efforts to legalize psychedelic drugs for personal use also appear likely to spread, after supporters poured millions of dollars into a Colorado measure that won approval.

Here’s a look at what’s next in the effort to reshape state drug laws.

MISSOURI AND MARYLAND

Recreational marijuana for adults 21 and older will become legal in Missouri on Dec. 8. That’s the same day the state’s existing medical marijuana businesses can apply for licenses to grow, manufacture, transport and sell cannabis for recreational purposes.