"I do think that that would be fair but I can understand that people would be a little apprehensive to take that road because there is a tradition of natural-born women, but today where there are so many surgeries and so many people out there who have a need to change for a happier life, I do accept that because I believe it's a free country," Culpo said.
Culpo said she was short and chubby as a girl, but blossomed after a growth spurt. She spent her summers at band camp after learning to play the cello in second grade. Her parents are also musicians, and her love for music saw her perform at Symphony Hall in Boston and Carnegie Hall in New York City.
Culpo is a 2010 graduate of St. Mary Academy Bay View, an all-girls Catholic school in Riverside, where she was a member of the National Honor Society. She is a sophomore at Boston University.
"Beauty is found in the way you treat others," she told pageant officials.
Rounding out the top five contestants were first runner-up Nana Meriwether of Maryland, second runner-up Audrey Bolte of Ohio, third runner-up Jade Kelsall of Nevada and fourth runner-up Jasmyn Wilkins of Georgia. As Meriwether and Culpo held hands waiting for the winner to be announced, Culpo bit her lip and cringed with anticipation.
Culpo demonstrated an outgoing personality throughout the competition, blowing a kiss and shimmying across the stage during the opening number. She cited starlet Audrey Hepburn as her source of inspiration, noting her many years of volunteer work.
"She was beautiful on the outside but also beautiful on the inside," said Culpo, whose favorite movie is "Funny Face."
Pageant officials also noted that Culpo "can tie a cherry stem with her tongue."
Miss Iowa USA Rebecca Hodge was named Miss Congeniality, and Miss Oregon USA Alaina Bergsma was named the most photogenic. They both won $1,000, but didn't make the top 16.
The pageant at the Planet Hollywood casino on the Las Vegas Strip had three competitions: swimsuit, evening gowns and interview question. Midway through the contest, pop band Cobra Starship performed as the beauty queens modeled their string bikinis. Singer Akon performed during the evening gown competition. Culpo had one of the more modest dresses of the contest, with many of the beauty queens wearing more revealing dresses with bare backs, high slits and sheer fabric.
The judge's panel included Chef Cat Cora, TV personality Arsenio Hall, singer Joe Jonas and reality TV star Rob Kardashian. Andy Cohen and Giuliana Rancic stepped in to host. Miss USA 2011 Alyssa Campanella crowned Culpo her successor at the end of the night.
She'll represent the United States at the 61st Miss Universe pageant later this year. An American has not been named Miss Universe since Brook Lee won the title in 1997.
The first-ever transgender contestant to compete in the Miss Universe Canada pageant made it to the penultimate round before losing her bid to win the title last month. She was initially denied entry to Canada's pageant because she was not born female. Donald Trump, who runs the Miss Universe Organization, subsequently overruled that decision.
Miss Universe publicity director Brenda Mendoza has said transgender competitors are now welcome at all of its pageants around the world.
The competition is not affiliated with the Miss America pageant.