yes, I’m very bored
I always thought that most large (research, not like public library main branches) libraries used the LOC classification scheme for their books, but I’ve stumbled into a few where that’s not the case - they are massive libraries and they use Dewey
what are the relative points in analyzing a library’s decision to use one over the other?
The Dewey system is flexible and easy to use, but not as hospitable to new fields of knowledge (which is important to academic libraries). Also, if I’m not mistaken, LC numbers are pre-assigned to new books, whereas Dewey numbers are assigned at the library; this makes the LC system appealing for rapidly expanding collections. There are also complaints that Dewey’s categories are not specific enough (you run out of numbers if you specialize), but that the LC is too US-based, which is why Dewey is translated or used overseas more than the LC. However, you can assign more than one Dewey number to a multidisciplinary work, which you can’t do in LC
LC or Dewey can be outsourced or in-house - I’ve done both myself. One of the bigger reasons to use LC for academic collections is that the numbers only get so big - Dewey numbers can be as big as you like, they’re additive. That means that the more specific (and probably skinnier) the book is, the longer the Dewey number is. They get unwieldy, so a lot of libraries truncate, and you end up with problems.
Both systems have their strengths and weaknesses. LC is tied to Thomas Jefferson’s personal library and Dewey is tied to the personal opinions of a seriously weird shyster and spelling reformer. You take the good with the bad.
Actually, it’s more often done by catalogers who work for the regional library system. There are also library jobbers (like Baker & Taylor) that will ship books already cataloged.
You don’t “run out of numbers” in Dewey because OCLC constantly revamps and reassigns numbers. (One of my favorite geek things to do is read the monthly updatesfrom OCLC.)
Frankly, I prefer Dewey because I find it far easier to understand how the numbers are constructed. There are definitely some odd juxtapositions in the 001-099 class, but for the most part the topics flow nicely into each other.
Yeah, like how gardening is in two completely different sections? 
Try to explain to a public library patron why garden design is on the second floor and gardening is on the third, especially since many books are really about both and sometimes it seems like the classification is totally at random?
The real world reason why some libraries use Dewey is that they got started in Dewey and didn’t want to have to undergo the pain of a changeover.
This is a pain, true, but it is more or less the only section this happens in.
Oh, except for the pockets of computer stuff that appear in various other sections, but those are now almost always cataloged between 004 and 025.
And …
[ul]
[li]Fiction/800s (since IME the vast majority of libraries that use Dewey only use it for nonfiction)[/li][li]Biographies/920s (and lots of other areas high in biographical books like the 780s, 810s, and 820s)[/li][li]Hi, Opal![/li][/ul]
Well, the “not Dewey stuff plus Dewey stuff” isn’t really Dewey’s fault. But it IS a huge problem. Sometimes I find copies of the same book down in fiction and in the 800’s. And fuck travel memoir.
Yeah, but putting fiction in the 800s is such a rare practice that I almost never see it done. There’s Beowulf, Don Quixote, Canterbury Tales, The Divine Comedy and Paradise Lost and that’s it. All other fiction is in the fiction section.
Really? We’ve got tons of “literature” hiding out there, particularly short fiction. (Sherlock Holmes is downstairs in fiction, but Poe is up in the 800’s. Go figure.) Not to mention plays, which confuses the merry hell out of people. Poetry for some reason surprises them less.
Poor Dewey all his hard work and someone goes an usurps him 
Ditto. Judging by the age of what I’ve seen, it was very popular among some catalogers for a while in the 1970s-80s to distinguish between “popular” and “classic” and put the former in the 800s.
Don’t feel too sorry for him. He was a horndog and a bit of shyster. Ever wonder why those card catalog cabinets don’t fit index cards? Okay, so the guy was a metric (and spelling) reformer… but he also owned the company that made the cabinets.
I named my first cat after him.