Some people are 'missing' from each of the census...
some people though are enumerated twice.
In 1910 that is the case with Otto Upton.
1910 census - Warren Co, PA
Here Otto is shown living with his parents and siblings.
1910 census - Spokane Co., WA
Here Otto (10 from the bottom) is in the wilds of Spokane Co., WA working in a logging camp.
1911 Canadian Census - Humboldt, Saskatchewan
But most surprising of all is that one year later in 1911, Otto appears in the Canadian census (3rd from bottom). He is working as a farm hand. Who knew?