Does an employer in Oregon need to tell you why you're fired?

In the United States, an employer can stop employing you at any time if you are an "at will" employee. If you didn't sign a contract that stipulates conditions under which you can be terminated, you are likely an "at will" employee. Otherwise, you would need to argue that there was an unwritten contract to prevent you from being terminated. If your employer didn't terminate you for misconduct you may be eligible for unemployment benefits.