Ten years ago the first-ever Record Store Day celebration took place at a Mountain View, Calif., vinyl shop called Rasputin Music. What might have been a blip on the pop music radar screen turned into a full-on phenomenon when members of Metallica showed up at the Bay Area store and hobnobbed with fans. 

The band loved it. The customers loved it. And all of those slightly odd characters who frequent independent music emporiums finally had a day to call their own. Record Store Day is a bit like Comic-Con for people who obsess over rare Smiths B-sides or Elvis Presley mono pressings.

Since that time, Record Store Day—celebrated on April 21 this year—has evolved into a global community event. Each year hundreds of artists head to record shops to perform, sign albums, socialize, and round out their personal collections. Festivities include cookouts, body painting, even parades.

“My introduction to all this great music and to ‘the music business’ came from hanging around, and eventually, working at independent record stores," says Wilco's Jeff Tweedy. "Nothing beats browsing in your favorite store, listening to music, finding something new or old that you’ve been searching for, all that. And without these stores, there’s just no way Wilco would still be around."

Dozens of labels and artists release new material specifically for Record Store Day, often limited editions. This year's offerings include everything from a picture disc of Courtney Barnett's "The Double EP: A Sea of Split Peas" to a 7-inch pressing of Florence + The Machine's "Sky Full of Song" to a five-LP box set of Johnny Cash's "At Folsom Prison: 50th Anniversay Legacy Edition."

"Record Store Day is now a worldwide phenomenon, celebrated on every continent except for Antarctica," says Michael Kurtz, co-founder of the event. "San Francisco, Sacramento, and Los Angeles are some of the biggest hunting grounds for vinyl lovers because you have great record stores there—stores like Amoeba, Dimple Records, Rasputin, Vacation, Permanent, Mount Analog, and Fingerprints." 

California's acclaimed record stores even attract shoppers from overseas: "A lot of Japanese collectors come to these stores to see what they can find," Kurtz explains.

All told, nearly 1,400 U.S. shops participate in the annual celebration, including several hundred in California, ranging from Fresno to Bakersfield to San Luis Obispo. (You can search the entire roster of participating stores here.)

Artists tend to love the event just as much as the fans: "There’s nothing as glamorous to me as a record store," Paul McCartney said after performing at Amoeba on Record Store Day. "I realized what fantastic memories such a collection of music brings back when you see it all in one place. This is why I’m more than happy to support Record Store Day and I hope that these kinds of stores will be there for us all for many years to come."

Many stores try to outdo one another, so it's worth checking around to see what they have planned. 

"I’ve heard that Patton Oswalt is appearing at Amoeba in Hollywood to meet fans," Kurtz says. "And I’ve heard that Derek Smalls (aka Harry Shearer, of This Is Spinal Tap fame) made a special 7-inch record, but in Spinal Tap fashion the record has arrived at the stores without the actual record inside, so he may be making an appearance at Amoeba to celebrate its non-release. I hope that fans show up."