United States Population 2015
According to the US Census Bureau's population clock, the estimated 2015 United States population (July 2015) is over 321.3 million. This differs a bit from the 325.1 million estimated by the United Nations.
By population, the United States of America is the third largest country in the world, a long way behind China (1.4 billion) and India (1.28 billion). Its most populous states are California (39 million) and Texas (27.2 million), and its most populous city is New York City (8.2 million).
Largest state in the United States
The largest state in the USA by population is California, which is estimated to be home to just over 39 million people. If California was a country, it would be the 36th most populous in the world, slightly larger than Poland. Its economy would be the eighth largest economy in the world, with roughly the same GDP as Italy, a European country of 61 million people. Interestingly, though, although California is the largest state in the United States of America, it isn't the largest state in the continent of North America - that honor goes to Brazil's state of Sao Paulo.
Largest city in the United States
The largest city in the USA is, of course, New York City. The city's population is estimated at an impressive 8.3 million, which makes New York City larger than the second and third most populous cities in the United States (Los Angeles and Chicago) combined.
For much of the early 20th century, New York City was the largest city in the world. The stunning growth of cities elsewhere in the world means that today, New York is only the world's 19th largest city, sandwiched between Bangalore in India and Dongguan in China. It is, however, the world's second largest city by GDP - its nominal GDP of $1.28 trillion puts it second only to the Japanese city of Tokyo.
United States Census 2010
The United States census is held once every ten years, to count the number of people in the country and find out basic information about them - for example, age, sex and race. The last census was held in 2010, and the next census will be held in 2020.
The information collected in the census is used for many purposes. The first purpose is to ensure that each seat in Congress represents roughly the same amount of people. Take a look at this video to see how Congressional seats are apportioned:
<iframe width="560" height="315" src="http://www.youtube.com/embed/RUCnb5_HZc0" frameborder="0" allowfullscreen></iframe>
National and State governments also use the information to plan services - for example, if they know that the population in an area is growing rapidly, they know that they will need to build more housing, schools and hospitals.
Every year, the Census Bureau releases annual population estimates. Statistical modelling methods are applied to the most recent census data to give an up to date picture of how the population of America changes between censuses.
You can read more about the census at the <a href="http://www.census.gov/2010census/">US Census Bureau website</a>.
United States Population History
Nobody is sure what the population of the Americas was before Columbus arrived in 1492, let alone the territory that is today the United States. Estimates vary wildly, but it seems to be accepted that the indigenous population of the Americas (the continents of North and South America combined) was between 50 million and 100 million in the 1490s. That includes approximately 15 million people living in the Aztec Empire and around 6 million Inca. The population of North America at the time is equally uncertain, and has been estimated at between 5 and 15 million.
Indigenous populations were hit hard by the arrival of European settlers. Firstly they were attacked by disease - some historians believe that over 50% of the population was killed by diseases such as smallpox. And yet more were killed by wars, massacres and resettlement programs. The Native American population of the United States reached a low point in the early 20th century, but has since been gradually increasing.
Formal censuses were not carried out during the colonial era, but records show that the colonial population grew from a shaky start of just 3,800 in 1610 to over 1 million in 1750. The population grew rapidly from then onwards and, when the first official census was held in 1790, shortly after independence, the population had grown to nearly 4 million.
United States Population Projections
The population of the US continues to grow today, driven by a high level of immigration. The latest data from the Census Bureau shows that <a href="http://quickfacts.census.gov/qfd/states/00000.html">US population growth is running at 0.9% per year</a>. They estimate that growth will continue fairly steadily over the next four decades, and that the US will reach a population of 400 million in 2039. If their predictions are correct, the US population in 2050 will be around 439 million. The united nations projects a much lower total, estimating a population of just over 400 million in 2050.
The country's racial profile will be vastly different, and although whites will remain the single largest racial group in the the US, they will no longer be a majority. Growth in the Hispanic and Asian populations is predicted to almost triple over the next 40 years.
The average US citizen of 2050 is likely to be older than the average citizen of today, and almost one in five people will be 65 or older. At the same time, the percentage of people who are working age (18-64) is likely to fall from 63% today to 57% in 2050. This will have huge implications for society as younger people work to fund the pensions and healthcare of the older.
Race and Ethnicity
In the census, people are asked to identify their race. The <a href="http://www.census.gov/prod/cen2010/briefs/c2010br-02.pdf">results from the 2010 census were as follows</a><ul> <li>White - 72.4%</li> <li>Black or African American - 12.6%</li> <li>American Indian or Alaska Native 0.9%</li> <li>Asian - 4.8%</li> <li>Native Hawaiian or Other Pacific Islander - 0.2%</li> <li>Two or more races - 2.9%</li> <li>Some other race - 6.2%</li> </ul>
This doesn't really tell the whole story, though, as it takes no account of those people who identify themselves as Hispanic. The census makes very clear that it does not consider Hispanic to be a race, but nonetheless it asks people whether they consider themselves to be of 'Hispanic, Latino or Spanish origin'. In total, 16.7% of people identified themselves as Hispanic - just over 50 million people. People who identified as Hispanic often identified themselves as White or Some Other Race as well, but this is not always the case.
In 2010, the census collected information about ancestry, but this question was removed from the 2010 census. The latest data from 2000 shows that these were the largest ancestral groups in the US:<ul> <li>German - 15.2%</li> <li>Irish - 10.8%</li> <li>African American - 8.8%</li> <li>English - 8.7%</li> <li>American - 7.2%</li> <li>Mexican - 6.5%</li> </ul>
United States Quality of Life
The average life expectancy of a person born in the United States in 2015 is 79.61 years. As in most countries in the world, US women have a higher life expectancy than men - women born in 2015 live for 81.88 years on average, while the life expectancy of men is just 77.3 years.
Compared to the rest of the world, using data compiled by the United Nations, the United States is only 39th in the world. Interestingly, both the US Virgin Islands and Puerto Rico have higher life expectancies than those born on the continental US. Hawaii is the state with the highest life expectancy (81.5 years on average) and Mississippi is the state with the lowest life expectancy (74.8 years on average).
Although the United States has the largest overall economy in the world, it does not have the highest GDP per capita. With a GDP per capita of $48,328, the United States ranks 11th in the world, way behind small countries like Luxembourg, with economies based around servicing international finance, but also behind some major countries including Canada and Australia. Average salary, calculated in 2011, is very similar at $45,230. The state with the highest GDP per capita is Delaware ($69,667) and the state with the lowest GDP per capita is Mississippi ($32,967).
Despite having a high GDP per capita and a healthy life expectancy, the United States ranks only 15th in the most recent World Happiness Report. Interestingly, considering the long standing battle over immigration at the Mexican border, Mexico actually ranks 14th. In the previous World Happiness Report in 2013, Mexico was also ahead of the United States, ranking 16th and 17th respectively.
<img style='max-width:100%' src='/images/worldhappiness.png'>
The language most commonly spoken in the United States is English, which is the main language of 80% of American residents. Spanish is the main language of 12.3% residents and Chinese is the main language of 2.3%.
Native American languages are the main language of 0.9% of residents. There is a wide variety of different Native American languages, many of which are on the endangered list. The most widely spoken is Southern Quechua, used by around 7 million people.
Although legal documents are normally written in English, the United States has no official lanaguage at the federal level. At the state level most, but not all states have English as their official language. Hawaii is the only state to have two official languages - English and Hawaiian.
The United States Constitution enshrines the right to religious freedom and prevents the development of an official state religion. The lack of official involvement in religion means that no questions about religion are asked in the census, and as a result, limited and sometimes questionable data is available.
The data on religion in this article and the associated chart is drawn from <a href="http://religions.pewforum.org/pdf/report-religious-landscape-study-full.pdf">a 2007 study conducted by the Pew Forum</a>.
It reported that the vast majority of Americans are believers in a single religion. According to a 2007 survey, 78% of respondents identified themselves as Christians. Just over half (51.3%) of all Americans are Protestants, and almost a quarter (23.9%) are Catholic. Other Christian denominations make up 3.3% of the population.
Jews (1.7%), Buddhists (0.7%) and Muslims (0.6%) are the next largest religious groups in the United States and 16.1% of Americans declared themselves to have no religion.