Sex Ratios of the u.s. Population Compared by Race and Ethnicity.
According to the Census Bureau, the U.S.population In 2003 was made up of 147.’ million.females (50.8 percent of the population) and 143.0 million males (49.2
percent of the population). Using this data. the Census Bureau computes the sex ratio (which it refers to as the male-female ratio) for various classifications of people
by multiplying the numberof males times 100, divided by the number offemales.
When the sex ratios for various racial or ethnic categories of people are compared, some pronounced differences are evident, as shown at right. As you can see. the categories with the highest male-female ratios (more males than females) are Latino/a and Native Hawaiian or other Pacific Islander. To determine reasons for differences in the sex ratio, it would be important to take Into account a number of factors, including the age of the people in the various categories. For exampie, up to age 24, the sex ratio of the U.S.population is about 105, reflecting the fact that more boys than girls are bom every year and that boys continue to outnumber girls until the age 35 to 44 category, when the ratio slips to 98.9. More than 63 percent of the U.S.Latino/a population is younger than 35 years of age, compared to slightly less than 47 percent of the U.S.white population. However, more than 57 percent of the African. American population in the United States is youngerthan age 35; if age were the only factor involved In One measure of population composition is the sex
ratio-the number of males for every hundred females in a given population. A sex ratio of 100 indicates an equal number of males and females in the population. If the number is greater than 100. there arc mort! males than females; if it is less than 100. there all’ more females than males. In the United States. the.estimated sex ratio for 2009 was 97. which means there were 97 males per 100 females. Although
approximately 124 males arc conceived for every 100 females. male fetuses miscarry at a higher rate, From birth to age 14. the sex ratio is 1.04; in the age 15-6-1 category, however. the ratio shifts to 1.0. and from 65 u ward. women outnumber men. By age 65. the sex ratio is about 75-that is. there arc 75 men for every 100 women. As “Census Profiles: Sex Ratios of the U.S. Population Compared by Race and Ethnicity” demonstrates. the ratio of males to females varies among racial and ethnic categories in addition to varying by age.For demographers. sex and age are significant population characteristics; they arc key indicators of fertility.
and mortality rates. The age distribution of a population has a direct bearing on the demand for schooling. health. employment, housing. and pensions. The current distribution of a population can be depicted in a population pyramid-a graphic representation of the distribution of a population by sex and age. Population pyramids are a series of bar graphs divided into five-year age cohorts; the left side of the pyramid shows the number or percentage of males in each age bracket. and the right side provides the same information for females. The age/sex distribution in the United Slates and other high-income nations docs not have the appearance of a classic pyramid. but rather is more rectangular or barrel-shaped, By contrast. low-income . nations, such as Mexico and Iran, which have high fertility and mortality rates, do fit the classic population pyramidpyramid. Figure 19.2 compares the demographic composition of Mexico, Iran. the United States. and France.