Are vintage dance cards that were used at dances in the early part of this century for girls to sign who they going with certain considered ephemera?

Yes, vintage dance cards are considered ephemera. Ephemera is a term used to describe items of collectible paper that have little practical use or value but are kept for sentimental or historical reasons. Dance cards fall into this category as they were used for a specific purpose in the past and are now regarded as mementos of a bygone era.