Years ago I got my Gr-grandfather's death certificate from Apr 1912
He had gotten significant intestinal damage from eating tinned bully beef in the Army in Florida while waiting to be shipped out to Puerto Rico in the Spanish American War 1898. His whole unit was affected and they had more casualties than the men who were fighting. Teddy Roosevelt campaigned on cleaning up the food industry, won and did that.
G-grandpa was sent to a veterans Fresh Air Camp in SD to avoid the harsh winters but died there about a year later. His mother had moved to Everett from Kansas. He did not appear on any of the published cemetery records for Mt Pleasant Cemetery, Seattle WA where he was buried according to his death certificate. G-Grandma came back to be with family in SD.
Years ago I traded some genealogy work for someone to go to that cemetery and what they found out was that the people from the Camp were considered indigent and buried in an unmarked section that was no longer maintained. She was upset and set about to do something about it, find the cemetery records and make them available and clean up that section and put a marker there.
People were buried on farms too. That G-grandmother's also died about 1911 on a Farm probably in Pierce Co ND according to the 1910 census and was buried on the farm. She died of "black measles" but even with online research I was not able to pinpoint what that might have been. It was finally mentioned on Dr Quinn Medicine Woman that that was the term they used to use for Rocky Mountain Spotted Fever. No death certificate was filed in ND according to a volunteer researcher but perhaps there was a spelling error or she was buried under her previous married name. He would only search one name.
Then there was Grandma Rosalie who was born out of wedlock in Holland but finally was legitimized with a generous donation to the local MN church in 1919. To do that her marker and church records just say she is just Mrs DeRyder so as not to tie her to her birth record (not the common spelling of our name) and her death certificate was also under that last name and for some reason did not show up on soundex matches when I first started looking. She died in an asylum of some kind, from family history I would guess from dementia, it is hitting many in my Dad's family as they hit 80. I think at that time those death records were sealed from the public along with some others and did not get in the old indexes.
Serendipity sometimes plays a role if you network with others looking for the same people. I linked up with a researcher who had married a Finland exchange student and moved there and we both knew about the second marriage for the Vet above's father, but we did not know about each others 1st and 3rd marriage. It opened up a whole other line of inquiry. That family had very, very common names.