The first thing is to narrow down the location that he died. This can be rather tricky, but there's a few ways to do it. Considering it's in the 1800's, you have a lot of options. Generally speaking, here's what you do.
- Try to compile as accurate of a timeline as you can. Find the last date that you have a record for. Census is a good start, use tax records if you can to narrow things down even more.
- Look at where family members lived after you lose record of your ancestor. If this person's wife was alive in 1900, and she lived in a different state, that gives you two potential locations where your ancestor died (Her new location, and the previous location). Children might also have moved, look in their locations as well.
- Narrow the window of time as much as you can. Again, this might be rather wide opened, but the narrower of a window you have, the easier it will be.
Okay, so you have narrowed down the location and time (Which I think you've done). Search for the records, and see what you can find. If you can't find anything that matches the locations/ dates, keep in mind that person might have moved in the mean time. I usually evaluate potential candidates by the following criteria:
- Is there any indicator that this person has relatives that you know? Is there a name mentioned on the headstone, or other family members in the same cemetery, for instance.
- Does the candidate have a record in the previous census that conflicts with your record? If you have a census record that matches their information, you probably have the wrong one. If, however, there is no information there previously, it is possible that the person moved.
- Is there any information from less reliable sources (Family trees, ancestry pages, etc) that matches the information you have suspected. If so, look at their sources, and perhaps contact the person who included the information if you can, it will all help to collaborate. I usually don't take these sources themselves as confirmation, but they do give a place to look for more information, and often they give the sources.
If you still don't have anyone, then open up your search locations, dates, re-investigate assumptions, and consider name changes. All of these could have results that might make it harder for you to find your information.