Since the United States became a country in the 1770s, immigration rates and ethnic composition have changed considerably. These changes included a shift from a primarily-European immigrant population (who, for the most part, voluntary immigrated) to a long era of slavery that forced the expansion of enslaved African populations. Additionally, there was another phase in US history that saw a large influx of Asian immigrants. These changes contributed to the highly diverse array of people from every country that is evident in contemporary American society.
Furthermore, because the population of indigenous American people declined in the first few decades of American independence and has remained relatively low, the majority of the US population has been composed of immigrants and their descendants.
Currently, ethnic composition is relatively diverse and has been increasing in recent years. People who self-identify as black or of-African-descent constitute about 13 percent of the population and those who self-identify as Hispanic or Latino account for more than 18 percent. As of 2016, more than 13 percent of US residents were foreign born, and of these about 45 percent are naturalized US citizens.