According to birth rates/immigration rates, by 2050 the United States will have a very high ethnically diverse population of Hispanic and Asian. So high, they will outnumber the caucasians/whites.
Thanks to the low birth rate of white people, interracial marriages, immigration and several other factors by 2015 that demographic will change to:
By 2030 however, the face of the United States will have so dramatically changed, it would seem like a totally different country.
By 2050, whites will be a minority, roughly the same as the asian population.
Language wise, the 3 major languages of the United States will be English, Chinese and Spanish. The languages will also blur significantly during the next 45 years, with english becoming a "melting pot" of other languages, hence "Ni hao Senor Americano!"
In case you are confused, the white, black and native population will not actually shrink. Those populations are expected to more than double by 2050. The problem is that percentage wise, they will seem to shrink in comparison.
Globally, Europeans/caucasians are already a minority compared to the growing Asian/Indian population. White people tend to have small families, whereas Asian & Indian families tend to be quite large. China has imposed "one child only" rules on its citizens in order to prevent over-population, but people continue to have multiple children anyway. Especially for Chinese who decide to migrate to other countries, one of the key motivators is so they can have large families.
The demographic change is not limited to the United States either. Canada, Europe, South America, Australia will also have radical demographic shifts. In the case of Canada, Asians will be the biggest population change. Europe will see an influx of blacks and arabs. Countries like Brazil in South America will see more blacks and asians. Australia, with its close vicinity to China and India, will see a huge influx of Asians and Indians.
"Ethnic Globalization" will be an important phrase during the 21st Century, as many ethnic groups will migrate to other parts of the world seeking work opportunities. Language wise, Mandarin Chinese (Pu-tong-hwa) will become more important than English as a business language. It will likely become mandatory in many business schools, and eventually mandatory in high schools around the world.
The world population in 2005 is 6.4 billion people (6,446,131,400 July 2005). The population growth rate is 1.15% currently. If that growth rate persists, then the world population will grow like this:
So by 2050 the world population will have reached almost 11 billion, and by 2100 almost 20 billion. Unless we have some major wars, diseases or some major "birth control" programs, environmental problems, the world's population is going to more than triple in the next 95 years.
In the future, green houses for growing extra crops will be an important part of the world economy. Meat will become more and more expensive, and often grown in "chicken factories" and fisheries. The idea of cattle grazing off the land will be an extremely expensive one. Land will become exceptionally valuable, and the possibility of wars being fought over territory is high.