Emilia Bradley, 15, was last seen by her family in York at 3.30pm yesterday (Thursday, March 14).
She said she was going for a run but has not returned home since, North Yorkshire Police said.
Police believe Emilia may have boarded a train and said she has links to Bolton and London.
Emilia is around 5ft 6ins tall, of slim build and has green eyes.
“We’re concerned for her welfare and we’re urging anyone with information to contact us on 101, select option one and provide reference number 12240045910,” a force spokesperson said.
