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United States Population and Key Rates

Figure 1 shows the US population for selected years between 1790 (the 1st US Census) and 2009 (estimated by the US Census Bureau). At its first official Census, the US had more than 4 million inhabitants, but it failed to count Natives, Blacks, and other racial groups. In the 219 years represented in Figure 1, you can see that the US population has increased nearly 78 times since its 1790 count-this taking into consideration all the births, all the deaths, and all the in-out migration. The US continues to grow in our day and will in coming years.

Figure 1. Estimated Population of the United States for Selected Years 1790-2009*

*Retrieved 9 April, 2009 from Table 1: Population Bulletin, Vol. 57, No 4 What Drives US Population Growth? Dec, 2002 http://www.prb.org/Source/57.4WhatDrivesUSPopulation.pdf; Statistical Abstracts of the US, 1997 Table 1; 2009 estimated retrieved from www.census.gov

Let's look at the birth rates for the US compared to the current highest birth rate state, Utah, and the current lowest birth rate state, Vermont, between the years 1991-2006. But, first we need to define rates. The Crude Birth Rate is the number of live births per 1,000 people living in the population. It's called crude because it ignores age-specific risks of getting pregnant. Figure 2 shows these rates and clearly indicates the higher rates for Utah in comparison to the US and Vermont. Before 1991, Alaska often competed with Utah for the highest state birth rate. Vermont is the lowest state rate today, but has also competed with Maine in past years.

Figure 2. Estimated Crude Birth Rates per 1,000 Population of the United States, Utah, and Vermont for Selected Years 1991-2006*

*Retrieved 9 April, 2009 from Table 77 Live Births, Deaths, Marriages, and Divorces: 1960-2006; Statistical Abstracts of the US and 1990-2006 from 1990-2006 data retrieved 9 April, 2009 from http://205.207.175.93/VitalStats/TableViewer/tableView.aspx

There are other rates to measure births between populations. Demographers use slightly different terminology than the average person when describing a woman's ability to get pregnant. True Rate is the "Number of events/ Number" at risk of the event. In other words, the Crude Birth Rate is not a true rate because it includes children, males and the elderly in the denominator of "1,000 population." To demographers, Fertility is a measure of the number of children born to a woman.

Total Fertility Rate is the total number of children ever born to a woman calculated both individually and at the societal level. Fecundity is the physiological ability to conceive or give birth to children. In Table 4 you can see some of the striking differences in Crude Birth and Total Fertility Rates. To understand these data you need to understand the term, More Developed Nations are nations with comparably higher wealth than most countries of the world including: Western Europe; Canada, United States, Japan, New Zealand, and Australia. Less Developed Nations are nations located near to or south of the Equator which have less wealth and more of the world's population of inhabitants including: Africa, India, Central and South America, most island nations, and most of Asia (Excluding China). China has the most strict fertility policy in the world and is often excluded from the rest of Asia in most official reports.



Table 4. Crude Birth Rates and Total Fertility Rates for Selected Regions and Countries*

Country or Region Crude Birth Rates CBR Total Fertility Rates TFR
More developed 1.6
Less Developed 2.8
Africa 4.9
Latin America/Caribbean 2.5
Asia (Excluding China) 2.4
China 1.6
Liberia 6.8
Canada 1.6
Mexico 2.3
United States 2.1
Italy 1.3
Japan 1.0
World 2.6

*From 2008 World Population Data Sheet: Demographic Data and Estimates for the Countries and Regions of the World.

Africa is the "birth hot spot" of the world and has been since about 1950. It has a projected population change of an increase of 100 percent between the years 2008-2050. A few African nations are higher and some are a bit lower. Uganda for example should experience a 263 percent increase while Swaziland should experience a 33 percent decline. The 6.8 TFR for Liberia means that the average woman is expected to have 6.8 children there. In the US it is only 2.1. This is an important indicator of population change because there is a principle which states that it requires a minimum TFR of 2.1 for the population to replace the man and woman who made the children and a TFR of 2.3 to begin to expand the population. Thus you can see from Table 4 that the less-developed regions of the world (especially Africa) are expected to grow, while the more developed (especially Japan) should not grow. Japan should decrease by 25 percent between 2008-2050.


Date: 2015-02-28; view: 1177


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