Native Population, by Age and Sex, for the United States: 2011
The most striking feature of the native age-sex pyramid is the “baby boom,” the increase in the number of people born after World War II between 1946 and 1964. In 2011, the baby boomers were between age 47 and 65, as can be seen by the relatively large size of those age groups in the age-sex pyramid. The years 1965 to about 1977 are often referred to as the “baby bust” because of the smaller number of children born then. The “baby bust” generation was between the ages of 34 and 46 in 2011, as can be seen by the constriction of those age groups in the age-sex pyramid. The “echo boom” or “boomlet” occurred between 1977 and about 1988, when many of the baby boomers had children who, in 2011, were between 23 and 34. In the older age groups, there are far fewer males than females. In most populations, women live longer than men. The dearth of males age 70 and older also reflects deaths during World War II. The shape of the age-sex pyramid of the native-born population is very different from that of the immigrant population.
There were 271.2 million native-born persons in the United States in 2011. Male-to-female ratio: 96.9.
US Census Bureau, American Community Survey, 2011.