early childhood
elderly person
young person
The American population continues to grow older, with the median age exceeding 40 in many states and the number of older men, in particular, increasing. Age data has been well tracked over American history: it is one of the few pieces of information, along with sex, that was asked in the original 1790 census and has been asked on every census since. [Source: Multicultural America: A Multimedia Encyclopedia; Age Distribution]
age distribution
children (age group)
concepts
composition of the population