Pot smokers in Washington state celebrated Thursday by lighting up under the appropriately-named Space Needle in Seattle as a voter-approved referendum legalizing recreational marijuana took effect.

Hundreds of smokers puffed joints and gleefully blew the smoke into the air as police stood by.

Under the new state law, people over 21 years old can not buy but they can possess up to 28 grams of marijuana for private recreational use. Public use is still forbidden and subject to a $50 fine, although Seattle police chose not to interfere with Thursday's outdoor pot party.

Voters in Colorado also approved legalized marijuana. That law does not go into effect until January 5.

U.S. authorities say marijuana is still illegal under federal law and banned from federal property and national parks.

A Quinnipiac University poll this week shows 51 percent of all Americans believe marijuana should be legal.