Despite the growth of the U.S. population during this period, the United States’ portion of the world’s total population has been declining compared to less developed, higher fertility countries where the population have grown more rapidly. The Census Bureau projects that the U.S. population will continue growing. The projection is that the population will be almost 440 million persons by the year 2050. The United Nations and the Social Security Administration, estimate that the U.S. population will be 404 million or 411 million respectively in the same year. The average annual growth rates between 1950 and 2000 were positive, however it has been declining over time. The average population growth rate in the 1950s was estimated to be 1.7% per annum while it decreased to only 0.9% per year during the year of 1980. The Census Bureau assumes that the growth rate will stay positive through year 2025, but will fluctuate over the time period. Tendencies in the size and growth of the U.S. population reflect the interactions of three underlying determinants: the fertility
Bibliography: CRS calculations based on data in United Nations, World Population Prospects: the 2008 Revision, Highlights, United Nations: New York, 2009, available at http://www.un.org/esa/population/publications/wpp2008/ wpp2008_highlights.pdf. U.S. Census Bureau, 2013 Resident Population at http://www.census.gov/. U.S. Census Bureau International Data Base at http://www.census.gov/ipc/www/idb/ranks.php. Free Demographics, www.freedemographics.com. United Nations Department of Economic and Social Affairs. World Population to 2300. 2004. Executive Summary, Page 2. United Nations Population Division Home Page, United Nations Department of Economic and Social Affairs