Hagan defeated Miss South Carolina Ali Rogers, who took second, and Miss Oklahoma Alicia Clifton, who finished third.
Hagan wins a $50,000 college scholarship and gets the crown for one year. Her platform was stopping child sexual abuse.
She is expected to spend her title reign on a nationwide speaking tour and raising money for the Children's Miracle Network, the organization's official charity.
Hagan defeated several other notable competitors who grabbed headlines this year because of their backstories.
Miss District of Columbia plans to undergo a preventive double mastectomy to reduce her risk of breast cancer, which killed her mother and grandmother.
Miss Montana was the pageant's first autistic contestant.
Miss Iowa has Tourette's syndrome.
And Miss Maine lost more than 50 pounds before winning her state crown.
The 92nd Miss America annual show held this year at the Planet Hollywood Resort and Casino on the Las Vegas Strip is the culmination of a week of preliminary competitions and months of preparations for the titleholders from all 50 states plus the District of Columbia, Puerto Rico and the U.S. Virgin Islands.
The pageant, which started as little more than an Atlantic City bathing suit revue, broke viewership records in its heyday and bills itself as one of the world's largest scholarships programs for women.
But like other pageants, the show has struggled to stay relevant as national attitudes regarding women's rights and civil rights have changed.
More recently, the rise of reality television has provided a superabundance of options for Americans interested in seeing attractive young people in competitive pursuits.