It is set in the southwest corner of County Armagh with the land boundary with the Republic of Ireland lying less than two miles away in both a southerly (County Louth) and westerly (County Monaghan) direction.

The origin of the name 'Crossmaglen' is uncertain. It has been interpreted as Cros-magh-gleana, "The cross of the shading plain" ⁽¹⁾, and Cros Mhic Lionnáin "McGlynn's crossroads" ⁽²⁾.

According to LP Murray, -

"The village of Crossmaglen is of modern growth....In the local folklore it was merely famed for a well-known ale-house or shebeen - kept by a man named Lennon. It will be noted that the 1766 Census gives Owen Lennon among the ---- inhabitants - and his house (or shebeen), which was probably at the crossroads, was the origin of the variant Cros Mhig Lionnáin. If the village is really named after a family, we would be inclined...to select the McCleans or MacClanes. There are no Flynns, and but one Lennon, in the Fews in 1602; but the MacClanes were numerous in all the Census lists...."⁽³⁾.

Lewis' Topographical Dictionary of Ireland 1837 has this to say about Crossmaglen -

Crossmaglen; a village in that part of Creggan which is in the barony of Upper Fews, County of Armagh and province of Ulster, 8 miles (NW) from Dundalk, on the road to Newtownhamilton; containing 545 inhabitants. It comprises about 100 houses, of which several are large and well built, and has a penny post to Dundalk: the surrounding scenery is strikingly diversified. In the vicinity is a small lake, called Lough Maglen, or Magheralin, and there are numerous others in the surrounding district. The slate quarries here were formerly worked to some extent, but they are now in a declining state.

A market for provisions is held on Friday; and there are fairs in the last Friday in every month for black cattle, horses, sheep and pigs. A constabulary police station has been established in the village; and a spacious and handsome R.C. chapel has been recently erected, which is the parochial chapel of a very extensive district, called Lower Creggan. A dispensary was built by subscription in 1830.