Around here, when HD was mad new, they were using rabbit ears to broadcast the signal. The Twin Towers was broadcasting the signal but after 9/11 obviously that stopped and they completely abadoned the system. If you want HD now, you gotta get it from digital cable from your cable company.
Either way, with the introduction and spread of HDTV, things are just really messy for television right now. In less than a decade, once HDTV becomes the standard (hopefully), everything should get sorted out.