Here are the companies known to have been raised primarily in Polk County --

4th (McNair's) Arkansas Infantry - Companies H-I.
19th (Dawson's) Arkansas Infantry - Company D.
24th Arkansas Infantry - Company H.
Newton's Arkansas Cavalry - Hale's Company.
Hart's Arkansas Battery.

I got an email from Ken, and I gave him my thoughts on where Isaac P. Howell might have gone after serving in the 4th Arkansas Infantry. I just happened to remember, however, that I read somewhere, years ago, that a company of Polk County men (or at least a large group of them) served in a Texas cavalry or partisan ranger regiment. I've always intended to follow up on this, but just haven't had time. There is also a possibility that he may have served in the Indian Territory. I don't know of any companies from Polk County which served there, but other western Arkansas companies did (from Crawford, Sebastian, Washington, Benton counties, possibly Scott County).