South Down (UK Parliament constituency)

South Down
County constituency for the House of Commons
Boundary of South Down in Northern Ireland.
Current constituency
Created	1950
Member of parliament	Margaret Ritchie (Social Democratic and Labour)
Created from	Down
1885–1922
Replaced by	Down
Created from	Down
Overlaps
European Parliament constituency	Northern Ireland

South Down is a parliamentary constituency in the United Kingdom House of Commons. It has been represented since 2010 by Margaret Ritchie, of the Social Democratic and Labour Party.

The county constituency was first created in 1885 from the southern part of Down. It was defined as including 'The Baronies of – Iveagh Upper, Lower Half, Lordship of Newry, and Mourne, and so much of the Barony of Iveagh Upper, Upper Half, as comprises the Parishes of – Clonallan, Donaghmore, Drumgath, Kilbroney, and Warrenpoint.'. In 1918, it was redefined as including 'The rural district of Newry No. 1; the part of the rural district of Kilkeel which is not included in the East Down Division; and the urban districts of Newcastle, Newry and Warrenpoint.' From the dissolution of Parliament in 1922, it was merged back into Down. Maps showing the component units of the constituency can be seen here.

The seat was re-created in 1950 when the old Down two MP constituency was abolished as part of the final move to single member seats. Originally the seat consisted of most of the mid and southern parts of County Down, with the north included in North Down. It was defined as including '(i) The urban districts of Banbridge, Downpatrick, Dromore, Kilkeel, Newcastle, Newry and Warrenpoint; (ii) the rural districts of Banbridge, Downpatrick, Kilkeel, Moira and Newry No. 1.' Of the post 1973 districts, it contained all of Down and Banbridge, together with parts of Newry and Mourne, Ards and Craigavon.