In general the South Fork [wikipedia.org/wiki/South_Fork_(Long_Island)] is considered to be all of East Hampton town plus the part of Southampton town east of Flanders Bay.
Towns and Villages and Hamlets, oh my!
Southampton Town
Bridgehampton
East Quogue
Flanders
Hampton Bays
North Haven
Northampton
North Sea
Noyack
Quiogue
Quogue
Remsenburg-Speonk
Riverside
Shinnecock Hills
Sag Harbor (part of)
Sagaponack
Southampton (village)
Tuckahoe
Water Mill
Westhampton
Westhampton Beach
West Hampton Dunes
East Hampton Town
Amagansett
East Hampton (village)
Sag Harbor (part of)
Springs
Wainscott
Sag Harbor
Well, is Sag Harbor in Southampton or East Hampton?
Yes.
I hate you! That's not an answer!
It turns out that the border between the TOWNS of East Hampton and Southampton runs roughly along Division Street in the VILLAGE of Sag Harbor.
West of Division Street is Southampton.
East of Division Street is East Hampton.
(Gee, I wonder why it is called "Division Street?")
Anyway, while we could identify each Sag Harbor business with the town that it sits in, at least for now we identify everything in Sag Harbor as in Southampton. This is wrong and we know it. But most of the businesses are on the Southampton side and we are feeling lazy.
Some day we will fix this, but be warned - it will not make things any easier for you.
East End of Long Island (source: US Census Bureau)
The East End of Long Island comprises five towns:
Riverhead
Southold
Shelter Island
East Hampton
Southampton
The East End is generally referred to as made up of the North Fork and the South Fork along with Riverhead and Shelter Island. Sometimes Shelter Island is lumped in with either the South Fork or the North Fork depending on who is speaking and how regionally chauvinistic they are.
South Fork and North Fork
Some people draw a line roughly north-south through the westernmost point of Flanders Bay, in Riverhead. Everything to the east of that is either North Fork or South fork.
Other people consider the South Fork to include all of Southampton and east Hampton.
If you can point us to an authoritative statement of what truly constitutes the South Fork, please do contact us at info@south-fork.info so we can revise our site.