I recently sent my eighth carton of Pagan magazines, dating from the 1970s to last year, to the University of California, Santa Barbara.
That particular UC campus is known for its religious-studies department. J. Gordon Melton, a well-known scholar of new religious movements, is also affiliated with the university, although not on the religion faculty. (From an academic perspective, Wicca, Asatru, etc. are "new religious movements", regardless of claims of antiquity that some people make for their traditions.)
Melton brought his own huge collection of material from his Institute for the Study of American Religion to the university library's American Religions Collection. That collection is now being digitized, which should make future study easier.
My last carton contained issues of Enchanté, Hole in the Stone, The Druid's Progress, and some other now-discontinued Pagan 'zines.
It's a hard choice: part of me wants to save everything indefinitely, the way some people save old car parts. The other part of me says that I am not in the archive business and that giving these publications to a real archive will make them available to others, not to mention freeing up significant shelf space in the garage (which can then be filled with Jeep parts).
There are a few boxes of back issues that I do hold on to: Green Egg, the best national Pagan magazine of the 1970s-80s; The Cauldron, continuously published for nearly 30 years now; Nemeton, a West Coast Pagan magazine from the 1970s, and my rarity, issues of The Pentagram, a British Craft newsletter published for a short time in the mid-1960s.