Yes, there has been a general drop in American ethics for decades. The Kennedy creed of "Ask not what your country can do for you" is faded from most people's minds, while social acceptance of being on the government dole has risen. But as always, fish rots from the head down; it is the political and business elite that has shown the way by shamelessly exploiting bail-outs, tax loopholes and outright corruption.
No, there hasn't been a drop in ethics in the U.S. However, over time there has been a change in the principles that govern ethical conduct in the United States, and this has generated a lot of conflict. As the nation becomes more heterogeneous, we are seeing more of a variety of ethical standards, and as a society we need to determine which of these standards will work best for us.
Not everyone follows the same ethical code, but most people have one. Most people still follow some sort of ethical code, even if it is not the same ethical code that their parents or their parents parents followed. Even if the ethical code has changed, there is still a sense of ethics.
It is easy to believe that ethics in the U.S. are not what they once were, but in actuality, the reverse is true. Rather than decay, Americans are more aware than they ever have been of moral and ethical issues, such as social justice, bio-medical ethics or what constitutes a just war. Not only news media, but popular entertainment, movies and television bring up and help explore various ethical quandries.