One difficulty with the online indexes to Griffith’s Primary Valuation (GPV) (1847-64) is there’s not a clear date for the individual record being examined. This is very important in your research because of family deaths and immigrations. In this case, we are talking about the date it was published verses the date the manuscript was generated. These differences can range from one to four years.
Now saying this, once you know the year GPV for a county was published, then you can subtract one to four years and make a decision as to how it affects your research. Was your ancestor even in the records!
GPV was taken by Poor Law Union, and the funds went for the support of the workhouses within the unions. These unions did not always respect county or parish boundaries. Because there are several unions covering each county, the years for GPV will vary. The chart below shows when GPV was published for unions covering a county.
If you know what civil parish your ancestor lived; then you can use a book such as Brian Mitchell’s A New Genealogical Atlas of Ireland (2002) to determine the Poor Law Unions which covered an area. If you only know a Catholic parish, then you can also use the maps to determine which unions covered the geographical area. The years for which GPV was published for each county are as follows:
Antrim (1861-2), Armagh (1864), Belfast City (1861), Carlow (1852), Cavan (1856-7), Clare (1855), Cork (1850-3), Donegal (1857-8), Down (1863-4), Dublin (1848-51), Dublin City (1849-50), Fermanagh (1862), Galway (1853-56), Kerry (1851-2), Kildare (1851), Kilkenny (1849-50), Leitrim (1856), Leix/Queens (1849-51), Limerick (1850-2),
Londonderry/Derry (1858-9), Longford (1854), Louth (1854, 1864), Mayo (1855-7), Meath (1854), Monaghan (1858-61), Offaly/Kings (1853-4), Roscommon (1855-8), Sligo (1858), Tipperary (1848-52), Tyrone (1858-60), Waterford (1848-51), Westmeath (1854), Wexford (1853), Wicklow (1852-54).
The main point is even if your ancestors had immigrated or died the year GPV was published, they may still be listed if you consider it was taken one to four years earlier. For more information on GPV I recommend the online article by the late James R. Reilly “Is There More in Griffith’s Valuation Than Just Names?”: www.leitrim-roscommon.com/GRIFFITH/Griffiths.PDF