SEATTLE (AP) — Tens of thousands of people are descending on a waterfront park in Seattle for what's billed as the nation's largest annual marijuana rally.

Seattle Hempfest's organizers expect as many as 200,000 people to attend the three-day event, and they say it has a pressing political edge this year. Washington is one of three states set to vote in November on whether to legalize the recreational use of marijuana under state law. Pot remains illegal under federal law.

Not all attendees favor Washington's initiative, even though it would allow adults 21 and over to buy up to an ounce of marijuana at state-licensed stores, and could bring the state billions of dollars in tax revenue. Some medical marijuana patients say its driving-under-the-influence provisions are too strict.

Many people smoke marijuana openly at the rally.