Officers say they are increasingly concerned for the safety of Abbie-Lea Bolshaw, 14, from Doncaster, who went missing on Sunday.
Lancashire Constabulary believe Abbie-Lea has links to areas of Lancashire as well as Manchester, and have appealed to the public for help locating her.
Abbie-Lea was last seen in the Asda supermarket on High Street, Carcroft, Doncaster, at around 2:20pm on Sunday, July 21.
In CCTV still from the supermarket, Abbie-Lea can be seen wearing a grey wig with dark roots.
She was last seen in a grey tracksuit with a green puffer jacket and dirty white trainers.
Police also say that Abbie-Lea has short grey hair, and think there is a possibility that she has removed her wig.
In a photo provided by officers, she has blonde hair, but police say she has since changed the colour.
Abbie-Lea has connections to the Manchester and Lancaster areas, and may be travelling using trains.
Police believe Abbie-Lea may have travelled into the Cumbria area after going missing.
Anyone with information can call police on 101 quoting incident number 536 of 21 July 2019.