High definition radio appears to be finally taking off in the USA. As most know, the USA's approach is "in-band, on channel", or IBOC, which doesn't utilize additional spectrum space.
One of the consequences of HD radio is that stations can air multiple channels of programming within their existing frequency bandwidth. The greatest number of channels I've seen for a single station so far is 3.
My web wanderings have turned up 3 public radio stations that offer the BBC World Service 24 hours per day:
WMUB, Oxford, Ohio (between Dayton and Cincinnati)
KNOW, Minneapolis/St. Paul, MN
KUOW, Seattle/Tacoma, WA
It has long been the dream of the BBC World Service to gain 24/7 access to leading USA cities, and it appears that for some, HD radio might do the trick.
Those who took the plunge into satellite radio in order to hear the BBCWS 24/7 might want to ask their local public radio stations to consider offering the BBCWS as one of their HD side channels. It might enable you to drop your satellite radio subscription.