In the United Kingdom, county lines drug trafficking is the practice of trafficking drugs into rural areas and smaller towns, away from major cities.

Traffickers recruit vulnerable children, including children in pupil referral units (PRU) who have been excluded from school, as drug dealers. Some young people are recruited via "debt bondage", whereby they enter county lines to pay off drug debts. Others take part of their own volition, owing to boredom and a lack of legitimate opportunity in marginalized communities.

The term "county lines" refers to the phone numbers, or lines, dedicated to this activity. The practice is also known by those involved as "going country" or "going OT" ("outta
town“).

Between the years of 2018 to 2019, National Crime Agency figures showed there were 1,500 drug trafficking routes of this sort in the United Kingdom, rising to 3,000; in that year the agency estimated the total turnover of county lines activities throughout the UK to be roughly £500 million. A 2020 report for the Home Office by Professor Dame Carol Black states that the county lines drug trade involved 27,000 young people in the UK.

In 2019, Sadiq Khan, Mayor of London, blamed cuts in police numbers for the rise of county lines gangs.

Also, in 2019, police said that they lacked the resources to tackle County Lines. They mentioned cuts to youth services may have been a contributing factor. They mentioned it was difficult to get the funding.

A 2020 report for the Home by Professor Dame Carol Black traces the causes of the phenomenon to a combination of government cuts in youth services and drug recovery services, absence of parents, poor parenting, increased child poverty, school exclusions, and availability of pure forms of drugs.

‘County lines’ is a term used to describe gangs and organised criminal networks involved in exporting illegal drugs into one or more importing areas within the UK, using dedicated
mobile phone lines or other form of “deal line”. They are likely to exploit children and vulnerable adults to move and store the drugs and money and they will often use coercion, intimidation, violence (including sexual violence) and weapons.

The government is determined to crack down on the county lines gangs who are exploiting our children and have a devastating impact on our communities which is why in November 2019, the Home Office established the County Lines Programme to enhance the response to this threat.

The County Lines Programme was launched by the Home Office in November 2019.

• Expanding the National County Lines Co-ordination Centre (NCLCC)
• Increased disruption on the rail networks by the British Transport Police’s County
• Lines Taskforce
• Targeted operational activity against lines, including 4 major exporting force areas:
  • Greater Manchester Police
  • Metropolitan Police Service
  • Merseyside Police
  • West Midlands Police
• Investment in new technology including Automatic Number Plate Recognition
• Increased support for victims

Since the County Lines Programme launched in 2019:

These figures are correct as of 11 December 2023.

Since April 2022, over 2,100 lines have been closed meaning the government has already surpassed its target to close 2,000 lines over the 3 years up to March 2025.