Can’t Find Grandpa Before 1850 In the US?

If you can’t find an ancestor who should be a head of household in a pre-1850 United States census, consider that he could be living with someone else and not listed by name.

I was looking for an older ancestor in 1840. Then it dawned on me that, given his age in 1840, he might have been living with one of his children. The ancestor would not have been head of household and would be “hidden” in one of those tally marks.