Miss California Alyssa Campanella waves after being crowned Miss USA 2011 during the Miss USA pageant in the Theatre for the Performing Arts at Planet Hollywood Hotel and Casino in Las Vegas, Nevada June 19, 2011. [Photo/Agencies]

LAS VEGAS - A 21-year-old auburn-haired California girl won the Miss USA crown on Sunday night and will represent the nation in this year's Miss Universe pageant in September in Brazil.

Alyssa Campanella of Los Angeles topped a field of 51 beauty queens to take the title at the Planet Hollywood Resort & Casino on the Las Vegas Strip. She strutted across the stage in a blue bikini with white polka dots and a dark turquoise evening gown with beading on its top.

She also answered a question about legalizing marijuana by saying she didn't think it should be fully legalized as a solution to help ailing economies.

"Well, I understand why that question would be asked, especially with today's economy, but I also understand that medical marijuana is very important to help those who need it medically," she said. "I'm not sure if it should be legalized, if it would really affect, with the drug war. I mean, it's abused today, unfortunately, so that's the only reason why I would kind of be a little bit against it, but medically it's OK."

Miss California Alyssa Campanella celebrates after being crowned Miss USA 2011 during the Miss USA pageant in the Theatre for the Performing Arts at Planet Hollywood Hotel and Casino in Las Vegas, Nevada, June 19, 2011. [Photo/Agencies]

Miss Tennessee Ashley Durham was the first runner-up, while contestants from Alabama and Texas placed third and fourth.

Campanella, a natural blonde, said she dyed her hair six years ago for a part in a play, for a "fiery" character with whom she found she had traits in common.

"It's really brought out the true Alyssa Campanella, I feel, and that's why I really enjoy being a redhead," she said.

Campanella replaces Miss USA 2010 Rima Fakih. The Michigan woman teared up as she walked across the stage for a final goodbye.

The pageant had three competitions: swimsuit, evening gown and interview question.

The contestants were whittled to 16 after the show's opening number, in which the beauty queens introduced themselves one-by-one. The top 16 were picked by preliminary judges through competitions and interviews during the week before the telecast. Celebrity judges picked the top eight after the swimsuit competition and the top 4 after the evening gown portion.