The National Library of Australia classifies anything pre-1900 as rare (different call numbers, location, storage, preservation and digitisation priorities/processes).
Anything post-1900 that is particularly valuable or rare (limited edition?signed by someone famous) may also get the 'rare' treatment.

Brendan Whyte
National Libray of Australia


> ------------------------------
>
> Date: Thu, 16 Oct 2014 14:15:09 -0400
> From: Theresa Quill <[log in to unmask]>
> Subject: Classification of Rare Maps
>
> Hi all,
>
> I'm in the middle of revamping what we consider "rare maps" and I was
> wondering if y'all have policies that spell out which maps are "rare". Do
> you do it by date? If so, what is your cutoff? Number of copies in the
> world? Relevance to your institution?
> For example, the USGS 15 and 30 minute topos are OLD but not necessarily
> RARE. We also have some newer maps that we hold the only cataloged copy
> for. So maybe there's a hybrid solution? If you do have a policy, would you
> mind sharing it?
>
> Thanks!
>
> --
> Theresa Quill
> Map/GIS Coordinator, Herman B Wells Library
> MLS Candidate, School of Library and Information Science
> Indiana University