To illustrate what you can expect to find in these key sites, I’ll use an example from my own research
. When I began looking for my second-great-granduncle John H. Pennington, I knew only that he was born about 1849 in Maine and his family was in the 1880 census of Glyndon, Minn. Soon thereafter, according to descendants, his wife and children returned to eastern Canada and he went to the West, but no one knew where. What became of him was a mystery.