Contraband in the form of lorry loads of live pigs make profits for smugglers and cost the tax payer.
The illegal transport of goods is big business along a border which is crisscrossed by an area of minor and unapproved roads.
Ever since the border was established in 1922, smuggling has been going on between the Republic and Northern Ireland.
While it is easy to see how small items can pass unnoticed across the border, it is difficult to imagine how lorry loads of squealing pigs can get across the border unchecked by the customs authorities.
An exact figure on the number of pigs being smuggled is hard to ascertain but estimates from the Northern Ireland Pigs Marketing Board put the number at around four thousand pigs every week. The incentive for the smuggler being a price differential of up to four pounds a pig.
The job is made more difficult for customs officials in that seized goods must be held in evidence for the courts. This is not easily done with a truckload of pigs. Furthermore, if the case does not stick, the customs authority is liable to pay compensation.
The border is dotted with farms making it easier for smugglers to traffic the pigs from north to south and vice versa.
Some of the smugglers are widely known yet they are not stopped.
Reporter Larry Sheedy spoke to a pig smuggler who goes by the name of John.
I'm told that the world and his wife believe that you are a pig smuggler.
John explains how the smuggling works and admits to making some money from his illegal dealings.
You might do fifty a day, some days a hundred and some days none.
This episode of 'On The Land' was broadcast on 23 September 1969. The reporter is Larry Sheedy.