Historically, the county was divided into eleven Baronies (Armagh, Fews Lower, Fews Upper, Lower Glenarm, Lower Orior, Oneilland East, Oneilland West, Orior Lower, Orior Upper, Tiranny and Upper Glenarm), though some Baronies straddle county boundaries. Each Barony encloses several parishes, but some parishes (and some townlands) straddle the boundary of two Baronies. Baronies are of interest to genealogists mainly because certain records are organised by Barony.

• Maps of Ireland and Northern Ireland, from CAIN [Conflict Archive on the Internet] Web Service
• Review - Journal of the Craigavon Historical Society:
  • Cassells, Brian, The Ulster Canal, Vol. 8 No. 2
  • Redmond, Jack, Whodunnit? A Lough Neagh map mystery of 1765, Vol. 7 No. 3

An overview of the relationships between counties, baronies, civil parishes and townlands can be found on this page.

• The Great Britain Historical Geography Information Service (GBHGIS) provides a mass of information about Britain's localities as they have changed over time. Information comes from census reports, historical gazetteers, travellers' tales and historic maps.
• A Vision of Britain Through Time, in the GBHGIS, provides maps and statistical information derived from census reports covering the period 1801-2001, searchable by place name or post code.
• The Association of British Counties (A.B.C.) "is a society dedicated to promoting awareness of the continuing existence of the 86 traditional Counties of Britain".
• British Counties, Parishes, etc. for Genealogists (archived copy).