The age and gender categories used in early censuses got more detailed as time went on. Average life expectancy was 35 in 1790, and the government was most interested in voters and men of military service age, so censuses didn’t need many categories. But by 1830, Uncle Sam was counting centenarians. When profiling your families for pre-1850 census searches, sort them into these categories:
free white males of 16 and upwards, including heads of families
free white males under 16
free white females including heads of families
all other free persons
1800 and 1810
These censuses had categories for both free white males and free white females in these age ranges: under 10, 10 through 15, 16 through 25, 26 through 44, and 45 and over. Separate columns count all other free persons and slaves, with no age or gender breakdowns.
For free white males and females, the 1820 census kept the same categories as in 1810, except for an added column breaking out free whites ages 16 to 18 (who were double-counted under those age 16 to 26).
Male and female slaves and free persons were counted in categories for those under 14, of 14 and under 26, of 26 and under 45, and 45 and upwards. A final column tallied “all other persons except Indians not taxed.”
1830 and 1840