This is the smallest division within a county and in the case of County Louth sizes vary from the townland of Longstones in Mullary civil parish at 0.79 acres to the townland of Collon in Collon civil parish at 4,348.23 acres. A large part of the townland system in County Louth is identifiable from the early fourteenth century. This administrative division remains in use today although it is being eroded in the towns and cities.
