The United States was founded by immigrants, early settlers from England established settlements in America in the 1600s like Jamestown, VA and Plymouth, MA. Slaves were than brought over from Africa to help expand the country with the British. Soon other groups started coming over to America for the great opportunities. The Chinese came in the 1800s for the California Gold Rush, The Irish came around the same time when The Great Potato Famine happened killing off Ireland's major food source. Other immigrant groups like the Italian, German, and other Europeans then started to come over to settle into the growing nation in the late 1800s. Then in the past 30 years Latin Americans have come here for a better way of life, looking for job opportunities. If you think about it your really not "American" your ancestry will date back to some Native tribe or another country on Earth, and remember America was founded by immigrants in the 1600s by Englishmen who discovered the New World when the Native Americans were here.
Obama's speech on immigration reform, from Las Vegas, Nevada.