I think the already mentioned Buck 110 and Buck 112 are excellent options. You could also take a look at knives by EKA Knivar, I know you asked for American made knives, but the EKA's are worth looking at. I own two of them and one of them is the Swede 60.
It is a tough knife that is/was also used by the Swedish army.
http://www.gotavapen.se/gota/artiklar/knivar/swed_knife.htm
It is a tough knife that is/was also used by the Swedish army.
http://www.gotavapen.se/gota/artiklar/knivar/swed_knife.htm