"So the question is, why was Overhills different and NOT part of Rock Resorts?"
Mike:
To answer that I'd say we need to remember that the Rockefeller family was one of the wealthiest and most powerful families in American history and they had a whole lot going on throughout the family branches and generations.
Percy Rockefeller who apparently started Overhills was the nephew of John D. Rockefeller who is generally referred to as "Senior." As you know JDR was the primary partner of Standard Oil, one of the largest corporations in early American business history. Some of his partners in Standard Oil or the financiers of the company read like a Who's Who of the Industrial Revolution and the late 19th and early 20th century business engine of America. One was Henry Flager who ended up owning a swath of the entire East Coast of Florida through his creation of the Florida East Coast Railroad and the opening up of Florida from Jacksonville to Key West.
In the second and third generations of families like that most all went to Harvard, Yale and Princeton and the rest of the so-called Ivy League colleges and from there they began to inter-marry and get into all kinds of business connections that included the primary avenues of finance, oil, railroads and many of the raw matters they carried, as well as high-level state and national politics and certainly including very high-level international diplomacy for some. Another of those families was Harriman. Averell Harriman was the son of E.H. Harriman who controlled the Union Pacific Railroad and who was arguably one of the richest men in America. Averell's avenue was finance (Brown Brothers, Harriman) and politics and international diplomacy.
These guys were the early 20th century American titans, and their business and social and family lives became remarkably connected and intertwinned. One of the places one finds those remarkable business, social and family connections today is in the histories of some of the most significant American golf clubs, particularly the likes of NGLA, The Creek, Piping Rock, and other similiar clubs around the country.
One of the things many of those hugely powerful families did in the latter half of the 19th century and in the beginning of the 20th century is buy up huge parcels of land throughout the south and the west.
Overhills was obvioiusly just one of many of those massive land holdings of those interconnected families that was originally used for personal and family reasons that lapped into places for all to get together for their favorite recreations, golf, polo, fox hunting, bird shooting etc and to talk over the things that interested those people which arguably included controlling or having a hand in what went on in business and politics and diplomacy all over the world.
If one were to do a business and family and social TREE of who these people were and how interconnected they were I feel it would be a real eye-opener to those on this site and it could even be stretched to include the clubs (including golf clubs) so many of them belonged to together.
I should note that between about 1837 and 1913 the United States did not have a central bank and essentially these were the people who stepped into that void and financed the burgeoning American nation and took control of many of its most essential goods and services (oil, raw materials, manufacturing, the railroads to transport them, banking and financial institutions and land---both private and resort!
RockResorts came later and I think that was just one of the interests of Laurence Rockefeller whose life was dedicated to venture capitalism, conservation of land and such. It may've been one of the later entities of what is known as The Rockefeller Brothers Trust (distinct from the Rockefeller Foundation) that was formed in 1940 by JDR's grandchildren (John, Nelson, Winthrop, Laurence and David).
Actually, a very good friend of my father's, Aldie Boyer, ran RockResorts and if I remember correctly he went to work in Rockefeller Center in mid-town Manhattan.