I've seen several funeral books that were saved by family members for over 50 years. I guess that is one thing that you won't ever throw away if it was for your spouse, parent or child.
I'm not sure when this custom started. It is surely an American tradition. Signing the book is something we make sure we always do.
I've done a little research and couldn't really find anything on when, where or who started it. Maybe it came along with the use of greeting cards in the early 20th Century since the books are made by some of the same companies. The Hallmark Company was started in 1910.
I suppose the purpose is to allow family members to see who was there for the funeral or visitation since they may not be too aware of this during the event.
My grandmother Edith Wilson Fulford saved two funeral books. One for her mother and one for her husband. Her husband Tink Fulford's book also has all the cards people sent or brought.
I scanned the pages of the one for her mother, Ida (actually she was named Idle) Day Lundy Wilson. My great grandmother died in 1956. In looking at these I recognize most of the names as family or friends.
Her son Walt was the first to sign and conveniently he put his relationship as son next to his name and then others on that page followed his lead.
I shouldn't be surprised that most of those who signed are now deceased themselves. Ida was a widow for over 20 years and most of the signatures are of women. Does that mean they came by themselves? The funeral was on a Saturday morning. Maybe their husband was present and just let the wife sign. I do that myself since my wife has a more legible handwriting.
We didn't attend the funeral since my family had moved to France just a couple weeks before her death.