re:For years the hospitable Blackwell's had been his winter quarters. Just as his more fortunate fellow New Yorkers had bought their tickets to Palm Beach and the Riviera each winter, so Soapy had made his humble arrangements for his annual hegira to the Island

i realised i for got to tell you the secret.. blackwell's island (now know as roosevelt island) was at one time home to a NYC jail.

(in US, in most stated, prision terms under 1 year are served in Jail, over 1 year are served in state penatentuaries)

i recognized blackwell's immediately..
Typhoid Mary was a guest at Blackwell's (the island also was home to a hospital for contagiously ill indigent people) for years.

As i have mentioned, NYC is an archipeligo, and its current jail (as any one who watches any one of versions of Law & Order can tell you) is Rikers (also a island)-anyone who flys into NY via LAG has most likely seen Rikers just before the plane has lands.. technically its part of the bronx, but its physically closer to queens, (and connected via a causeway to queens)

of its many island, about 40 are inhabited...(Hart's island is only inhabited by the dead, its home to NYC's potters field)

many of the island have changed names over the years, the names were usually the name of the 'last major land owner of the island'