Colbi S. Cooper, reported missing to Biloxi police, was last seen Saturday in the 2400 block of Beach Boulevard, police say.
The area is near the Mississippi Coast Coliseum and Convention Center.
Cooper may have some mental issues, and is wanted as a welfare concern, police Det. Christopher De Back said in a news release.
She was wearing a camouflage-style backpack, a turquoise shirt under a navy blue jacket and gray Nike shoes, De Back said.
Police released a picture of her Monday and asked for information from anyone who has seen her or knows of her whereabouts.
All callers can remain anonymous, De Back said.
To give a tip, call the Biloxi Police Department Criminal Investigation Division at 228-435-6112 or Biloxi Police Dispatch at 228-392-0641. Or give a tip by emailing the Criminal Intelligence Unit at firstname.lastname@example.org.