Out here we vapor barriered walls and cathedral type ceilings, but not ceilings that had attic space above. That was over kraft faced batts many years ago. Now days with kraft facing, a vapor barrier isn't mandatory, but I would do it anyhow. You dont want to vapor barrier the underside of the floor joisting.

Thanks, sierra. I'll probably put up the vapor barrier (every little bit helps right?). But should I use fiberglass under the floor (in the crawlspace) or something else?

Here's a link to insulating the crawl space "conditioning " it rather than insulating between the floor joists. You will have to research if this would be beneficial in your climate zone compared to insulating the floor joists. Conditioning the crawlspace means eliminating venting while insulating the floor joists would typically be a a vented crawlspace application. Here's a couple of links on the subject:

http://www.buildingscience.com/documents/information-sheets/5-thermal-control/crawlspace-insulation/?searchterm=conditioned crawlspace

Here is a link that might be useful: conditioned crawlspace

Before you dive in to insulating, please do a little research on insulating historic homes. Houses in 1850 were not designed to be insulated or have vapor barriers. Some modern techniques can cause older homes to retain too much moisture and lead to rot.

New York State Building Code requires a vapor retarder on any wall, ceiling or floor that makes up the 'thermal envelope' of the structure.

In your case, you need a vapor retarder on all your walls, ceilings and floors.

This should be already intact if you used kraft paper faced fiberglass insulation with the paper face oriented to the warm-in-winter side of the floor, wall or ceiling.

If you have any remaining questions, call your local Code Enforcement Office for detailed assistance.