Back in 2008, Record Store Day (RSD) was launched as a hopeful holiday aiming to buck up struggling independent music retailers desperate to lure customers.

The situation was dire. The Tower Records chain had closed in 2006, and CD sales were shrinking. Vinyl was an outmoded format that barely amounted to a drop in a music industry bucket with a hole in it.

"The general consensus," says Record Store Day cofounder Carrie Colitton, "was that record stores were dead."

The seventh Record Store Day is set to take place on Saturday. More than 1200 retailers across the country are selling limited-edition merchandise and hosting events - including Philadelphia shops like a.k.a. music in Old City and Main Street Music in Manayunk. The mom-and-pop music store glass is half-full.

A big reason is that sales of vinyl have increased sixfold since 2008. Last year, CDs, hurt by the growth in streaming Internet services such as Spotify and Pandora, fell another 14.5 percent. Digital sales declined for the first time since the advent of iTunes.

But vinyl increased 32 percent - rising from 4.5 million units in 2012, to more than 6 million in 2013, according to Nielsen SoundScan.

This year, there will be 450 RSD-specific releases hitting stores, up from "between 10 and 20" in 2008, according to Colitton, who oversees the Raleigh, N.C.-based Record Store Day along with partner Michael Kurtz as an unpaid vocation. (In her paid job, she's director of marketing for Dept. of Record Stores, a coalition of indie record stores.)

Among the choice selections: Bruce Springsteen's American Beauty EP, featuring four unreleased songs; LCD Soundsystem's Live at Madison Square Garden; and It Takes A Nation Of Millions To Hold Us Back, the vinyl reissue of the classic by Public Enemy, whose rapper Chuck D is this year's official RSD ambassador.

Evidence of the vinyl renaissance is apparent throughout pop culture.

Saturday will see the release of Eilon Paz's Dust & Grooves: Adventures in Record Collecting, a gorgeous coffeetable book that depicts 130 enthusiasts with their collections, including Philadelphians Big Rich Medina, King Britt, Skeme Richards, and Aaron Luis Levinson.

Portlandia comedian Carrie Brownstein's American Express TV commercial in a record store has been viewed 10 million times on YouTube. (She and co-star Fred Armisen also mocked Portland-based chain The Ace Hotel, where all suites have turntables, in a 2011 sketch.)

The British documentary Last Shop Standing: The Rise, Fall and Rebirth of The Independent Record Store will screen at Hideaway Music in Chestnut Hill at noon on Saturday.

Director Alex Steyermark's movie The 78 Project, which captures musicians like Victoria Williams and Ben Vaughn making 78 rpm discs on a 1930s Presto recorder, premiered at the South By Southwest Film festival in March. In July, Amanda Petrusich's Do Not Sell At Any Price: The Wild, Obsessive Hunt for the World's Rarest 78rpm Records will be published by Simon and Schuster.

Paz started the Dust & Grooves project as a website after he moved to Brooklyn from Israel in 2008 and spent most of his underemployed time crate-digging. (The launch party, with 20 DJs, will take place at Powerhouse Arena in Brooklyn on Saturday. Info at Dustandgrooves.com.)

Vinyl has become cool again "because of digital music," Paz says. "The natural thing to say would be that the mp3 killed vinyl. But I think it's the opposite, actually. The lack of a physical, tangible medium brought vinyl back to the people.

"We don't change, really," adds Paz (who quips that one thing record collectors have in common is "most of them have cats"). "Times change, technology changes. But our basic need to hold, to feel things - vinyl let's you fulfill those needs."

It also sounds good. "The sonic quality of the vinyl format is so warm and full compared to all digital mediums," Medina, the Fishtown-based DJ, tells Paz in Dust & Grooves. "It's ridiculous. There is no reputable argument for that point."

"I think it's happened because of the anonymity of the digital age," says Grammy-winning producer Levinson. He estimates his wide-ranging but salsa-centric collection at 6000 LPs and another 1000 or so 78s. "Just as the slow-food movement has come back, and craft beer has come back, records have come back. People are once again prizing something of quality that has human scale and authenticity and personality to it."

As a diehard enthusiast, Levinson enjoyed the era of CD dominance "because all sorts of people were dumping amazing records. I had so much less competition. Now it's really hard to get good records. Everybody wants them."

That's good for stores like Old City's a.k.a., which will host a four-band bill on Saturday with Ortolan, A.M. Mills, Gardens & Villa, and Lushes. New shops are opening, like Phoenixville's Deep Grooves, and the oversized new Rough Trade store in Brooklyn.

Pat Feeney of Main Street Music says vinyl accounts for 40-50 percent of sales. "I'd say it's doubled in two years," he says. Current hot sellers are Beck's Morning Phase, The War On Drugs' Lost in The Dream, and Nas' Illmatic reissue.

"I have a circle of customers who've gone 100 percent back to vinyl and don't even want CDs. A lawyer from Collegeville bought a $3,000 turntable and comes in every week to buy vinyl."

"Every year it gets bigger," he says of RSD. Last year, "we did a month's worth of business in a day." Birdy, The Gantry, and others will play for free Saturday afternoon at Main Street Music.

Jon Lambert manages the Princeton Record Exchange, where prog-rock band The Dinner performs at 5. RSD's impact has been "surprisingly deep and meaningful. If you told me seven years ago that we would have over 300 people lined up waiting to buy records on a Saturday in April, I would have thought you were delusional."

Record Store Day isn't only about vinyl. There are also exclusive CD releases. RSD's Colitton, who says most of the more than 200,000 people who follow RSD on Facebook are in the 18-to-35 range, stresses that most LPs come with a download card for "digital convenience."

Vinyl made its comeback, Colitton thinks, because "it's a very physical, human way to interact with new music. It's a ritual almost. You pick up the record. You probably clean it. It's like a Japanese tea ceremony. I love my phone, I love my headphones. But even for the young people who grew up with digital music, I don't think anyone wants to live their entire life in front of a screen."

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@delucadan