There covergae is all over the US.
I have working in the canyons of Utah, 60 miles of dirt road and 100 miles from town
and always had a good signal for my Sirius.
I swear by sirius and have worked from west Texas to North Dakota and the only
problems I had was I wore out the receivers from over use. Meaning I put prob 100k miles 2 years in a row driving to and from rigs.