The suspects include people from Merseyside, Bradford, Manchester and Middlesbrough.
The 'county lines' model sees organised criminals from large urban areas exploiting children and vulnerable people and forcing them to travel to smaller towns and cities such as Scarborough, York and Harrogate to sell drugs, often using violence and intimidation.
North Yorkshire Police set up an operation, Project Shield, in response.
Detective Chief Inspector Graeme Wright of North Yorkshire Police, who is leading Project Shield, said: “There has always been drug dealing, but ‘county lines’ is of particular concern to the police due to the exploitation of vulnerable people and the violence used to control them.
The latest arrest took place today in Scarborough, when officers raided a property in the town. A 44-year-old woman was arrested on suspicion of possessing class C drugs and theft. Police seized drugs from the premises as well as items suspected as being used in the supply of drugs, including weighing scales, sim cards, a mobile phone and suspected stolen property including a passport and bank card.
The woman remains in police custody.
It follows two arrests in the Filey area, seven in York, two in the Thirsk area and three in Harrogate since the beginning of the month.
On Wednesday (October 10), police raided a home in Bell Farm, York, where they found four people, including a 16-year-old boy and 18-year-old man, both from Merseyside, along with a man and woman from York, both aged 37.
The two suspects from York have since been released under investigation and the two suspects from Merseyside have been released on conditional bail while the investigation continues.
In a separate incident in Thirsk on the same day, officers arrested a 21-year-old man from Middlesbrough on suspicion of being concerned in the supply of class A drugs.
He has been released while the investigation continues. Cash and equipment believed to be used in the supply of drugs were also seized from a property.
The previous day, on Tuesday (October 9), two men aged 27 and 52 were arrested in the Filey area on suspicion of conspiracy to supply class A drugs. They have been released under investigation.
On Monday (October 8), a 47-year-old man of no fixed address was arrested in Harrogate and later charged with possessing heroin. He is due to appear at Harrogate Magistrates’ Court on October 25.
On October 4, an 18-year-old man from Manchester and a 37-year-old woman from York were arrested after the vehicle they were in was stopped on Bootham in York.
They were both arrested on suspicion of possessing class A drugs with intent to supply. They have been released while under investigation.
On October 3, a 25-year-old Bradford man was arrested in Harrogate and charged with possessing class A drugs with intent to supply, and money laundering.
He was remanded in custody and appeared at York Magistrates’ Court the following day where he was again remanded in custody and sent to Crown Court for trial.
On October 1, officers stopped and searched a 41-year-old man on East Parade in Harrogate who was arrested on suspicion of possessing class A drugs with intent to supply. He has been released while under investigation.
A further arrest for drug driving was made in the Thirsk area on October 11, after concerns were raised for the driver of a vehicle. The female driver was tested for drugs at the roadside and subsequently arrested on suspicion of drug driving and possessing a firearm.
Police believe the woman is also the victim of 'cuckooing', in which organised criminals target a vulnerable person and often take over their home to use as a base for drug dealing.
The force said it was taking steps to safeguard her welfare.