While doing a little research this morning on what all the numbers in those columns at the top of the page in the 1790 census means, I discovered this little gem about the 1820 census. I did not know this!!!!
 _________    A note about the 1820 census____________

The 1820 Census has caused many a family historian to spend a considerable amount of time hunting a male that didn't exist or to follow the wrong family because of the age breakdown columns. The 1820 census added a column for Males 16-18 years of age.
*****What is not readily apparent to the family historian is that any males listed in this column are also listed in the 16-26 column.**** The government wanted an idea of the number of males that could qualify for military duty so the additional column for males 16-18 was included on the census form.
The instructions for the US Marshals for the 1820 census says: "It will be necessary to remember, that the numbers in the columns of free white males between 16 and 18 ... must not be added to the general aggregates ... the number will be repeated in the column of those between 16-26"

~Trish~