I think it only covers certain areas.
Link to XM Radio
Traffic & Weather Boston/Philadelphia 210 Local Traffic/Weather
Traffic & Weather New York City 211 Local Traffic/Weather
Traffic & Weather Atlanta/Miami 212 Local Traffic/Weather
Traffic & Weather Dallas/Houston 213 Local Traffic/Weather
Traffic & Weather Washington/Baltimore 214 Local Traffic/Weather
Traffic & Weather Pittsburgh/Minneapolis 215 Local Traffic/Weather
Traffic & Weather Detroit/Las Vegas 216 Local Traffic/Weather
Traffic & Weather Chicago/St. Louis 217 Local Traffic/Weather
Traffic & Weather Tampa/Orlando 218 Local Traffic/Weather
Traffic & Weather Phoenix/San Diego 219 Local Traffic/Weather
Traffic & Weather San Francisco/Seattle 221 Local Traffic/Weather
Traffic & Weather Los Angeles 222 Local Traffic/Weather