The operation was based in Liverpool and used young, vulnerable recruits to ferry drugs between Merseyside and the Yorkshire seaside town.
Its ringleader, Thomas Dean, 28, from Liverpool, has now been sentenced to seven years in prison for conspiracy to supply crack cocaine and heroin.
One of his co-conspirators, Adam Harwood, 27, of Walton, Liverpool, was jailed for six years and nine months.
Another member of the gang, Christopher Michael O’Donoghue, 49, of Cherry Lane, Liverpool, was jailed for five years.
A fourth member, Matthew Williams, 26, of Elmore Close, Liverpool, was given a 10-month suspended sentence for money laundering.
Six other members of the gang, described as foot soldiers, were jailed in 2017 for a total of 17 years and five months.
North Yorkshire Police today said they hoped the dismantling of the network – which operated between July and November 2016 – would send out a clear message to other criminals.
Det Con Phil Nockels, of Scarborough’s serious crime unit, said: “Thomas Dean was the ringleader of this conspiracy – supported by his co-conspirators, he manipulated and threatened other people further down the chain to carry out his dirty work for him.
“[This] outcome sends a clear message to those who travel to North Yorkshire to pedal drugs and exploit vulnerable people – we won’t tolerate it, regardless of where you live and how far you travel, we’ll find you and bring you to justice.”
County lines crime is a relatively recent phenomenon in which drug traffickers use extreme violence while trying to expand their markets from big cities to smaller towns.
Dean began establishing himself as the main drug dealer in Scarborough after he was released from a spell in prison connected to similar offences in Weston-super-Mare.
Following typical county lines operating methods, he used a branded phone line to target drug users in the town and, during the period of the conspiracy, more than 25,000 text messages were sent in bulk via the line, advertising drugs for sale through local dealers recruited by the gang.
Harwood was one of Dean’s trusted middle men, with the investigation showing he had spent considerable time in Scarborough bringing drugs into the town and taking the proceeds back to Liverpool.
O’Donoghue was a drug user himself and would perform various roles for Dean and take his payment in drugs.
A vehicle bought by Dean was insured in O’Donoghue’s name and he then took the blame for a speeding offence as well as the possession of a samurai sword found in the vehicle.
Williams allowed his bank account to be used for the laundering of the proceeds of the drug sales.
A number of locals were ‘cuckooed’ by the gang during the conspiracy – slang for the practice of dealers taking over people’s homes and using them as bases for the storage and selling of drugs.