IRELAND 101
"A brief geography, history, and genealogy lesson."
The Northridge
family reportedly originated in England, the central province of today's United Kingdom.  From here, the family spread to Ireland, Canada, the United States, and Australia.
The "Emerald Isle" of Ireland contains both the "Northern Ireland" province of the United Kingdom and the Republic of Ireland.  Northern Ireland was established following a civil war during 1916-1923.  The entire island is roughly the size of the state of West Virginia.
I know, the map is hard to read.  The island of Ireland contains four provinces: the Northern province of Ulster (purple), the Western province of Connaught, the Eastern province of Leinster, and the Southern province of Munster.
The Northern province of Ulster contains nine counties; eight of these are found within the borders of present-day Northern Ireland, belonging to the United Kingdom.  The ninth province, Donegal, is a member of the Republic of Ireland.
The Southernmost province of Munster contains six counties: Clare, Tipperary, Waterford, Limerick, Kerry and Cork.  Cork is the Southern-most of the eight and the focal point of much of the ancestral research. 
County Cork
Munster Province
Ireland
1. The city of Cork, the capital of County Cork.

2.  Bandon, a primary cross-roads between the city of Cork and the port of Clonakilty.

3.  Clonakilty, and the Port of Clonakilty, the primary emigration port for many of our ancestors.

4.  Dunmanway, a recurring parish in the birth, death & marriage records of our ancestors.

This map depicts the
Irish Diocese which existed
in Ireland's early history. 
The Diocese of Cork & Ross along the Southern area
of County Cork were the primary focal points of the genealogical research.