Corcoran's Who Occupied Land as Noted in Griffith's Valuation, County Mayo, Ireland
The County Mayo Griffith's Valuation was conducted between the years of 1855 and 1857. Costello Barony was the only Barony out of the 9 that did not have any documented Corcorans at the time the Valuation was completed. Tirawley Barony in North Mayo had far and away the heaviest concentration of Corcorans with 67 occupying property. Carra Barony came in second with 19, Burrishoole Barony with 13, Kilmaine Barony had 10, both Clanmorris and Gallen Baronies had 8, Murrisk Barony had 7 and Erris Barony in Northwest Mayo had only 6.
A closer look at Tirawley Barony shows Addergoole and Crossmolina Civil Parishes having the most Corcorans of the 15 parishes in this barony (having 18 and 15 respectively). There were 10 Corcorans in Kilmaclasser Civil Parish in Burrishoole Barony and the rest of the civil parishes had 8 Corcorans or less. Take a look at my Corcoran Surname Distribution Map to get a better understanding where the Corcorans in these civil parishes were located. The website Ask About Ireland has a great section allowing you to search the Griffith's Valuation. They even have maps that zero in on the occupied land, which you might want to take a closer look at. I have referred to this amazing resource to document the Brennans, Corcorans, Gahagans and Coffeys that were present in the County Mayo and County Roscommon Griffith's Valuation.
There is one caveat to keep in mind when looking at these findings from the Griffith's Valuation: The Griffith's Valuation only includes the individuals (occupiers) who own, lease or rent a parcel. For instance it will list a householder but not the individuals who live with him. It was common in County Mayo for individuals to share parcels, particularly of land (The Rundale system of communal land sharing). Sometimes the whole town shared one parcel of land. Shared parcels may or may not be with related individuals. Just because an individual is a lone occupier of a parcel does not mean that he is living in (house) or tilling (garden) this parcel alone. He may have numerous family members living with him, but they will not be listed unless they actually lease or own the parcel. Occupiers who sublet their acreage of land or houses to others will be listed as landlords.
Corcorans Listed by Civil Parish
(Griffith, 1847-1864;2003, County Mayo)