Morgan Foster, 16, was last seen at around 11.30pm on Saturday 29 February.
She is known to have links in Rochdale, Greater Manchester, Liverpool, Blackpool in Lancashire and Colwyn Bay in North Wales.
Morgan is described as white, 5ft 3in tall, of slim build, with shoulder-length blonde hair. Morgan speaks with a Liverpool accent.
Officers are becoming increasingly concerned for Morgan and want to make sure she is safe and well.
Anyone with information about Morgan’s whereabouts is asked to DM @MerPolCC, call 101 or contact @missingpeople on 116 000.