American Bittern

This is a clapper rail Rallus crepitans, though there's a chance that it could be a Virginia rail Rallus limicola.

I agree; it's clearly one of the Rallus rails based on the vertical stripes on the flanks. The gray checks and the subtle barring on the flanks make me lean toward this being a Clapper Rail too. Clapper Rails are also more common and more likely to be acquired as non-releasable rehab. birds.