OFBSLF is correct, but they are heavily or completely subsidized by the FAA. I understand, that if a local community wishes to close a local airfield that has received FAA subsidies, then that money must be paid back to the FAA. In some cases it is this 'debt' that prevents airfields, built years ago in the country but now surrounded by housing, from being taken over for or by developers.
Regards,
White Bear.