2 People
The United States’population was more than 308 million in 2010 according to the national census taken that year，and is officially estimated at about 321 million as of 2015.The country’s population density varies by region;the northeastern part is densely populated，while most of the area between the Mississippi River and the Rocky Mountains is sparsely populated.For many years，there has been a trend of population movement to the west coast，resulting in California becoming the most populous state in the country with a population over 38 million as of 2014.The least populated state is Wyoming，which has only 584，153 people.
The majority of the population is white，accounting for about 72％ of the total in 2010.Whites are descendants of settlers and immigrants from Europe.Through most of American history，the core of the population were white Anglo⁃Saxon Protestants（sometimes called WASPs）who traced their origins to England.The descendants of English settlers make up about 45％ of the American population today and control much of the wealth and political power in the nation.White Americans also include immigrants and their descendants from Germany，France，Ireland，Italy，Spain and other European countries.
The rest of the population includes as Native Americans，Hispanics，African Americans and Asian Americans.Native Americans are descended from the original inhabitants of the continent.They have been known as Indians because when Christopher Columbus arrived in America，he thought he was in India and named the people there accordingly.Researchers believe that the ancestors of Native Americans migrated to the American continent about 10，000 years ago across a land bridge where the Bering Strait lies today.The number of Native Americans was greatly reduced after white people arrived in America，most were killed by war and European diseases such as small pox.The rest were gradually forced into isolated，often desert areas known as Indian reservations.Native Americans account for only about 1％ of the total population of the United States，whereas there are believed to have been around 50 million native peoples living the Americas in 1492 when Columbus arrived.
Hispanics，known as Latino，are the fastest growing minority group in the United States.The origin of Hispanics is mainly of Nicaragua，Mexico，Salvador and Guatemala.With a population of about 51 million，they are the largest minority group in the country，making up around 16 ％ of the total American population.The populations of Hispanic and white overlap significantly.Most Hispanics live in the southwestern states，including Arizona，California，New Mexico and Texas.Since Spanish is some Hispanics’first language，many schools in these states use Spanish in teaching classes.
Blacks，also known as African Americans，are the second largest minority group in the United States with a population of about 39 million.Blacks make up around 13％ of the total American population.The majority are descendants of slaves brought over from Africa.Today，more than 85％ of blacks live in major cities，such as New York，Chicago and Washington D.C.New York’s population includes about two million blacks，and around 60％ of the residents of Washington D.C.are black.
Due to a variety of historical and social factors，including racism，relatively high percentages of blacks and Hispanics live in poverty and depend on government welfare programs.
The number of Asian Americans in the United States has grown rapidly in recent years.Asians make up about 5％ of the population today，compared to only 1.5％ in 1980.Asian Americans are spread out across all parts of the country，with California and New York having the largest Asian populations.Hawaii is home to the highest percentage of Asian American residents.Asian Americans trace their origins to many countries in Asia，including China，India，Korea，Japan，Vietnam and the Philippines.
Chinese Americans constitute the largest Asian subgroup in the United States.The first Chinese arrived in California in the late 1840s.Chinese immigrants contributed greatly to the construction of the transcontinental railroad during the 1860s.After the railroad was completed，many of them opened laundries in California.Others worked in gold mines and on farms，as well as on land reclamation and irrigation projects.Some also entered the fishing and manufacturing industries.
Racial prejudice led the U.S.Congress to pass the Chinese Exclusion Act in 1882，which banned further immigration from China.The act was not repealed until 1943 when China became an ally of the United States in World WarⅡ.The Gentleman’s Agreement between the United States and Japan in 1907 effectively stopped immigration from Japan.Asians in general suffered from discrimination and were not allowed to enter certain careers in the past.However，the situation has changed since the 1960s.Today，many Chinese Americans have moved into professions such as science，medicine and education and distinguished themselves in various fields，with six having won the Nobel Prize.
As a country made up of many different ethnic groups，the United States has long been described as a“melting pot”，in which immigrants from different backgrounds have traditionally cast aside many of their old cultural traits and adopted a new identity as Americans.This process of assimilation traditionally included learning the English language and adopting American beliefs，customs and manners.One result of this tradition is that 92％ of the total population aged 5 and over have no difficulty in speaking English.
However，many Americans tend to regard the nation as a racially divided society.Racial differences underlie many social，cultural，political，economic and religious divisions in the United States.Some scholars believe that it is healthy for American society to preserve the different cultural traits of its people.Rather than a melting pot”as a symbol of American society，they prefer the image of a“salad bowl”in which different peoples mix together while maintaining their distinctiveness.Although the United States has outlawed racial discrimination since 1965，the problem continues to exist.