Speaking of "pockets": From what I can tell from history, all of Ohio was copperhead-ville.
A lot of it was. Even more of a reason why the Civil War should not be thought of as a simple North versus South affair. There's many great things about the South but the political Confederacy was not one of them.
Ohion provided 320,000 troops for the Civil War, third only to New York and Pennsylvania. Lincoln also beat McClellan by 13 percentage points in the 1864 election. Your claims of copperhead influence is widely exaggerated.
The so-called Copperheads were some of the biggest cowards alive during the war of southern rebellion. It only took the sight of a Union soldier marching in formation to set these fifth columnists scurrying for their holes. Sound familiar?