Many contracts have a severability clause, which states that even if some part of the contract is thrown out or unenforceable, the remainder of the contract remains in effect. For example, "Contract 1" might say that you cannot do (A), (B), (C), or (D), and Contract 1 also has a severability clause. If a court found that it is illegal to ban people from doing (C), Contract 1 would still prohibit you from doing (A), (B), and (D).
But supposing "Contract 2" does not have a severability clause - it just says you can't do (A), (B), (C), or (D), and there is nothing in the contract about what happens if part of the contract is unenforceable. As before, a court finds that you can't ban people from doing (C). Would this result in the whole contract being thrown out or just the (C) part?
I'm not sure if this is state-specific, but if I need to specify a state, let's say Oregon.
(Note: This is not a duplicate of this because that question only asks about the UK and Germany.)