Alexander Crosby knows the difference between west coast, east coast and dirty south rap music. He can talk about St. Louis and the Midwest’s burgeoning rap scene, too. That isn’t because Crosby necessarily likes crunk or hyphy – he has to.

Crosby, the development librarian for the Las Vegas-Clark County Library District’s adult collection is in charge of purchasing the new electronic media for the 12 urban and 12 rural libraries within the system. He’s paid to know what’s popular in rap. And gospel. And Latin. And every other genre Clark County residents are interested in.

“[At first,] I had no idea there were so many times of different types [of rap],” says Crosby, who has worked in collection development at LVCCLD for more than a decade. “If you get into Latin music… there are dozens of types.”

Crosby finds learning the ins and outs of so many genres fascinating, but admits it can be a daunting task. As of Sept. 30, LVCCLD owned 188,514 music CDs in the adult collection, which have been circulated 1,104,322 times. Meanwhile the children’s collection includes 18,552 CDs, which have been circulated 102,539 times. That’s a lot of music to stay updated on.

At the Clark County Library, located on Flamingo Road, a quick scan ready-to-be-shelved cart shows how diverse the catalog is. There’s the latest Killer’s album, an Afro-Latin Party compilation, hip-hop artist Colby O’Donis, DJ Paul Oakenfold, Primus, John Mellencamp and a CD titled Party Time Karaoke.

Crosby and his collection development staff watch Billboard charts, CMJ and other music monitors for popular and new releases. He pre-orders the new releases with the goal of having the CDs in the library shortly after they’re available in stores. Many potential patrons, Crosby says, don’t realize that the library makes a concentrated effort to have the newest material.

This may be in part because so much of the collection is checked out. According to Crosby, 45 percent of the library’s collection is out at any given time. “What you see here is often the least popular material,” he says, thumbing through the rock section of the racks.

Crosby explains that reserve lists exist for all materials, so when those sought-after items are returned, they are immediately sent back out. Information on availability, including how many holds are on a given CD can be found at the LVCCLD Web site. According to the site, The Flaming Lip’s newest release, Embryonic, has 17 holds on it and is in the cataloging process, while young pop star Selena Gomez’s Kiss & Tell has 77 holds and is expected to arrive at the library soon.

Recently, Crosby reached out to Theory of Flight after seeing the local band gain press over its debut CD. Crosby hopes that he can expand the library’s music to include more local bands, but admits it’s difficult to sift through which bands will be around long enough for people to take notice. Plus, tracking down bands and purchasing CDs isn’t as easy when you’re the government. Bands must be willing to donate the CDs (as Theory of Flight did) or allow the library to invoice them.

Crosby believes the library could be a great resource for local bands and adds, “People can hear a band in a bar and the next day check out their music, listen to it sober.”