There was a wonderful article at The Chronicle of Higher Education discussing the use of library consortiums to save money and space.
"Talk of digital revolutions and bookless libraries notwithstanding, academic libraries around the country are feeling the squeeze as legacy collections outgrow shelves, and shelves give way to learning commons and shared study areas. Those twin pressure points—too many print books plus new demands on library real estate—have spurred academic libraries to try a set of state and regional experiments to free up library space to suit modern learning styles and still make sure that somebody, somewhere, hangs onto books that make up part of the intellectual record, even if those books haven't circulated in years."
But how do libraries decide which books to deselect? According to the author of the CHE article, "they should draw on solid data—on persuasive and detailed analyses of what's in a collection and how it's used and whether those books are available somewhere else." Some libraries have "settled on three criteria: titles that were published or acquired before 2005, that appeared in at least three collections, and that had circulated three or fewer times since 1999."
It's been a slow movement toward digitization and de-duplicating, but "[m]ass-digitization projects, notably the creation of the HathiTrust digital repository with its nearly 11 million volumes, have also encouraged libraries to act. If electronic copies of monographs exist, that takes some pressure off libraries to have print copies of them close by. (About 3.5 million of the digitized works in the HathiTrust are in the public domain, according to the repository)."
Nearly every academic library is facing space and money constraints, and regional consortiums are a great idea. But it can be a challenge to consider another library when building or weeding a collection. There has to be a strong foundation of trust. There can also be issues of access to resources. If only one or two copies of a print monograph are saved for archival purposes, the libraries that house the monograph may not be willing to lend it through interlibrary loan or other because there is a risk that if a patron or library loses the book, it will be lost forever.
As libraries continue to change and evolve, I suspect that we will see many more consortiums pop up. Our job as librarians is to work out the kinks to archive our intellectual record.