An American is someone born and subject to US authority, or having gained citizenship by parents or naturalization, according to the US Constitution ("Thinking of Becoming a U.S. Citizen?").
More Than Citizenship
Being an American, though, requires more than that; first, it means being able to possess more independence, stability, and democracy than any other nation in the world. An American is someone who respects and defends the constitution of the United States, and everyone else supports America. Being an American often involves learning the meaning of the history of the country and what it contributes to the nation's existence. Ideally, Americans are persons who believe in the formation of the Constitution in order to create a perfect union, ensure domestic tranquility, ensure justice, and promote the welfare and liberty of the citizens and the country.
The American Dream
Being an American comes with the benefits of living the American dream. Contrary to common misconception, an American dream is not about life accomplishment but the idea of living a simple and fulfilling life with faith and equality as the most important features. It also entails living in liberty and a country of unlimited opportunities. The American dream also has a lot to do with the US being a nation of immigrants, who hoped to live better lives in the new world than in their countries of origin. Lastly, the American dream entails the belief that everyone in the society can achieve anything through hard work and determination. As can be seen, the American dream reminds the people of the sacrifices and struggles of the forefathers. Therefore, as an American, one should always remember the key aspects which make the US a unique and memorable country. The American dream is certainly one of such features.
"Thinking Of Becoming a U.S. Citizen?" USCIS, 2013.