Sometimes when you have hit a genealogy stumbling block it helps to go back and use another method to find a lost relative. For example, you may find your great-great-great grandfather in the 1880 census, but you can't find him in the 1870 censes even though he would have only been 15 at the time. He should have still been living at home, but there is no sign of him.
If you've tried everything else you can think of, go back to the 1850 census. Find the names of all of HIS father's brothers and sisters and follow them through the census records. It's possible at the time of the census, your great-great-great grandfather was working or apprenticing with an uncle at the time.
