Brennan'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. All 9 baronies had Brennans living in them at the time the valuation was completed. Costello Barony on the Southeast side of Mayo had the highest concentration of Brennan land occupiers with 80. Gallen Barony (which borders County Sligo) had a total of 47 Brennan's, and Carra Barony (in south Mayo which borders County Galway) had 46 Brennan occupiers. Tirawley Barony in North Mayo had 12 Brennans, Clanmorris Barony in South Mayo had 9, Burrishoole Barony on the eastern side of Mayo had 5, Kilmaine Barony and Murrisk Barony in South Mayo each had 4 and Erris Barony in Northeast Mayo had only 1 Brennan.
Costello Barony's Kilbeagh Civil Parish which borders both County Sligo and County Roscommon had a large Brennan contingent with 16 Brennans and 6 Brannons. Annagh, another Costello Civil parish had 19 of the 80 documented Brennans. The highest concentration of Brennan's in Gallen Barony was in Kilconduff Civil Parish. Drum Civil Parish had by far the highest number of Brennans in Carra Barony with 19.
Griffith's Valuation documents individual land occupiers in each civil parish and townland. I have organized them by Civil Parish and further by Townland within each parish. Take a look at my Brennan Surname Distribution map to get a better understanding where the Brennans 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. The Ask About Ireland Website and Cultural Heritage Project is coordinated by the project team at Chomhairle Leabharlanna.) 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.
Brennans listed by Civil Parish
(Griffith, 1847-1864; 2003)