ABSTRACT
This chapter presents a general description of the demography of the United States. With 252 million persons, the United States ranked as the third most populous nation in the world in 1991, after China with nearly 1.2 billion and India with nearly 870 million. Population change results from two components: natural increase, which is the difference between the number of births and deaths, and net migration, the difference between the number of persons moving into and the number moving out of an area. Population growth in the United States is increasingly dependent on immigration. The age and sex composition of a population are important because certain biological characteristics, legal rights and responsibilities, and socioeconomic characteristics are a function of one's age and sex. Race and ethnicity are commonly used to refer to differences among population groups based on cultural, historical, and national-origin characteristics. Ethnicity generally refers to the national, cultural, or ancestral origins of a people.
