In a recent posting, I made a reference to the "bedroom counties" of New York City, meaning the suburban counties surrounding the Big Apple. The term was based on "bedroom community," which is defined in the dictionary as a suburb. You can get more specific, as some suburban locales are more destinations in themselves, but the context was more geographical than socioeconomic.
I actually googled the term and found only one use prior to mine by Kansas State University economist David Darling:
A bedroom county is where more people live in the county than work in the county - the daily net flow of people coming into work is smaller than the net flow out.
Darling's use never took, perhaps because, as he acknowledges in his work, some bedroom counties are also job centers. My own home county of Westchester, for example, has long been filled with bedroom communities popular with Manhattan commuters, but many municipalities here, such as Yonkers, New Rochelle and White Plains are small cities popular as employment locations. This makes Darling's rigid numerical definition awkward for use in real estate. Bedroom communities were defined over the years more by their location more than numerical statistics. First and foremost, they are good places for commuters to live.
Bedroom counties in my view therefore are suburban counties that are commuting distance from a major city. I would characterize the bedroom counties of New York City as Westchester, Rockland and Putnam to the north; Fairfield in Connecticut; Nassau and Suffolk to the east; and in New Jersey, Bergen, Hudson, Essex, Union, Passaic and Morris counties. You can differ if you wish. I never won an argument with anyone from Somerset County, NJ anyway. All metropolitan counties of New York are also job centers, but they are also all suburban and that locational component trumps who works where in this day and age.
If, at some point the commuter population of Westchester were to overtake the population of those who sleep here I would still consider it a bedroom county. It is one of only two counties to physically border New York City. We are in real estate. It is a location thing.