Anyone who resides anywhere south of Maine, any area typically referred to as "Boston". Anyone driving a vehicle without a cracked windshield and working directionals. These people are typically middle class white folk from the suburbs of Boston, Hartford, NYC etc. Flatlanders are not to be confused with the masses of particular people streaming south from Quebec to Old Orchard Beach.
That flatlander from New Jersey just asked the mountain man, "At what age does a deer turn into a moose?"
The flatlander was standing there in cargo shorts and told the raft guide, "I can't go swimming right now, i don't have my bathing suit."