Your options are pretty much the following: history teacher, museum guide, historical site guide, management at either of the previous two, archivist for a government or large and old corporation, adjunct instructor at the college level, professor at same, or move on to law school. It is not a field with a lot of openings.
Library Science is in fact a viable option for history majors, as both compile information. Librarians though, store & retrieve it; historians interpret it.