PS:

I've wondered about the possibility of emmigration too, and have also wondered ... in censuses, maybe Thomas was called by another name at home. Maybe a persons first name was actually Bill and they entered Bill in the census, but they were actually called by their middle or nickname "John" at home and by everyone. Who knows. Those census records also often have misspellings or sometimes even nicknames etc. Information was only as good as it's provider.

Cross referencing info to make the connections with other info is good.

Also, if someone who normally "lives there" is temporarily away and living elsewhere, then they will show up wherever they were living, or at, at the time of the census. Kids often lived with relatives for a while, etc. Any number of reasons someone would not be listed as living at that household at the time of the census taking. Makes for interesting searching, and often really creative searching to locate people, especially so far back