Never been near the Ozarks myself but big black cats keep cropping up all over the place don't they. We get reports round Yorkshire too, had one myself about 15 years back on the moors - massive thing, longer than any dog I've ever seen, jet black and low to the ground. Took a photo but it came out blurry like they always bloody do.
Three times in a month is significant though. Are you seeing it in the same spot each time? Could be territorial, following a regular route. Worth checking if theres a ley line running through that area, sounds daft but these sightings do cluster around certain geographical features and I've seen it too many times to dismiss it.
What time of day roughly? Ours was dusk which apparently is typical.