My Opinion: Nearly All Cushings from Cork, Limerick, Tipperary Area are Related

The whole point of that table was to show that Cushing (or it's Irish variants: Cushen and Cussen) was not a very common name in Ireland.  The estimated number of Cussens in about 1840 was 800.  To play around with some numbers (I'll try to use more accurate numbers after I do a little research), if a typical family is two parents and six children, 800 Cussens is about 100 families.  Almost all of these, nearly 80%, were in southwest Ireland.  Roughly using the population chart at http://www.mapspictures.com/ireland/history/ireland_population.htm , there were about 50 Cussen families in 1790 and only about 25 in 1700.  We'll never trace individual Irish Cussen families back to 1700, but I think it's certain that the Cussen/Cushen/Cushing families from southwest Ireland are somehow related.