I have been told on good authority that the following families came to St. Croix from County Fermangh Ireland, beginning in the early 1830's: Balfour, Fleming, Patterson, and Latimer. County Fermangh borders County Cavan on the northwest, so this adds to the families previously identified as arriving from that region
We might be able to narrow things even more, for some indications suggest a clustering in the Frederiksted area of County Cavan immigrants. Tramping through the Frederiksted Cemetery recently, I came across a monument for John McCabe ("native of Co. Cavan Ireland who died 11 Oct 1890, aged 66 [erected by his nephew Patrick Brady]"); a pair of tombstones for Gaffneys ("Thomas, born Aug 7 1871, Co. Cavan, Eire, died Sept. 8 1939, St. Croix"; and "Ellen, nee Gallagher, born June 4, 1873, Co. Cavan, Eire, died Oct. 16. 1947, St. Croix"); and tombstones for Farrellys ("Mary E. 1888 - 1937" and "Patrick A. 1877 - 1951"), a family known from other sources to have come from County Cavan. Others buried in Frederiksted Cemetery include Hewitts: John ("b. Ireland - d. St. Croix 9 Dec 1895; 51 yrs." and Robert ("b. Ireland - d. St. Croix 11 Aug 1899; 38 yrs") and John T. Armstrong ("22 Jan 1911 - age 52 yrs"). Again, there is evidence that both the Hewitts and Armstrongs were from County Cavan.
Was 19th century Frederiksted a center for County Cavan arrivals? Curiously, I came across no graves on which the person was said to have come from some other county in Ireland; although I could well have missed some. If nothing else, the graves of John McCabe and the Gaffneys suggest that being born in County Cavan was regarded as noteworthy.