Just to satisfy my own curiosity, I checked on the number of Antenna Structure Registrations over the last four years to see what they showed in terms of site growth. (courtesy of Chuck Pergrim of Percon) As most of my readers will know, the FCC does not require Antenna Structure Registrations for all towers, particularly those that do not require FAA notification. (Typically under 200′)
In 2001, when the old TOWAIR tower registrations were changed to Antenna Structure Registrations by the FCC, there were 89,000 listed sites.
In 2002, there were 96,000.
In 2003, there were 101,000.
In mid 2004, there were 104,000.
Currently, there are 109,538 ASRs.