Pretty certain that it's not a Cooper's Hawk. Cooper's Hawks are in the genus Accipiter, whereas the bird in the photo by the original poster looks to be in the genus Buteo, which are heavier bodied (the Rough-winged hawk pointed out is a Buteo).
A good feature for identifying Accipiters (in North America, that includes Sharp-shinned, Cooper's, and Goshawks) is their proportionately long tails. In the photos posted by Mitsuman and Occam, have a look at how far the tail extends past the wing tips, then compare that to the original photo.
So what is the bird in the original photo? Could be any of the local Buteos, and it looks like it might be a young bird, fledged this year, which are usually more brown in color than adults. So I'd want to start with geography, then check which Buteos breed nearby, then check which of those have banded tails (like the Accipiters do).
I find myself wanting to apologize for being a bird dork...