These forums sometimes will not let me post a U R L. Just the same, look at the coverage map for VirginMobile USA.
That coverage map shows where Sprint has native coverage. Of course if you occasionally go out of that area there is some roaming coverage too.
From a cursory glance, it looks like they have coverage in the area, but study the coverage map first. Hopefully someone in this forum will have some first-hand experience to lend.
I occasionally drive to Spokane from Oregon, but that just tells you the highway is covered.