Nationally it's only used by T-Mobile in very small amounts of spectrum, and only as fallback of last resort or for legacy things like burglar alarms. Regionally, there might be some rural specialty carriers using it (stuff like indigo wireless for the mining industry).
AT&T shut their footprint off completely a few years ago to free up spectrum in 850mhz.
Correct me if I'm wrong, but I believe EDGE has been disabled across a lot of the US.