Most genealogists use federal census records on a regular basis. Few resources are, after all, as packed full of information and as easy to access as a census. And, while we all know that the details found in a census can often be incorrect, this helpful record collection has become a family history staple for good reason. No other resource recorded details about our ancestor’s lives in such a frequent and predictable way and, often times, the federal census may seem to be the only method we have to explore our ancestors’ lives between birth, marriage and death. However, a recent comment by a Family History Daily reader reminded us that there is another related resource group that many people researching US ancestors are either unaware of, or regularly underuse. And it’s a very valuable one.