This constituency comprised the southern part of
County Armagh. From 1885 to 1918 the constituency was bounded to the north and north-west by Mid Armagh, to the south-west by South Monaghan, to the south by North Louth, to the south-east by the Borough of Newry and to the east by South Down. In 1918, that part of the constituency in the urban district of Newry was added to the South Down constituency. Between 1918 and 1922 the neighbouring seats were the same except that Louth was an undivided county constituency and Newry had been absorbed into South Down.
1885–1918: The barony of Orior Upper, and those parts of the baronies of Fews Lower, Fews Upper and Orior Lower not contained within the constituency of
Mid Armagh.
1918–1922: That part of the existing South Armagh constituency comprised in the administrative county of Armagh. Prior to the
1885 United Kingdom general election and from the dissolution of Parliament in 1922 the area was part of the
Armagh constituency. ==Politics==