ROCKLAND — If you know your blues, you know that the genre comes in about a dozen shades from the box guitar solo sound of the Delta blues to the smoother, jazzier tones of West Coast blues. But even if you’re not an aficionado, you will undoubtedly recognize the electrified, hard-driving edge of Chicago blues that gave rise to rock ‘n’ roll.

This year’s North Atlantic Blue Festival, July 16-17 in Harbor Park, has devoted the entire Saturday slate to the Chicago sound and features performers from the Midwest mecca. Legends like Eddy “The Chief” Clearwater, Billy Branch, and Lonnie Brooks will take the stage with the amped up energy that characterizes Chicago blues.

As if Saturday’s tribute isn’t enough, Sunday’s lineup offers up-and-comers Trampled Under Foot and superstars Eric Bibb and Robert Cray.

As soon as last year’s festival ended, promoters Jamie Isaacson of Wayne and Paul Benjamin of Rockland went to work putting together the 2011 weekend just as they have for the past 18 years.

“That’s the fun part,” Isaacson said. “Paul and I were fantasizing about who’s out there, who could we get, who’s available. I think this year is one of our strongest lineups ever.”

Having tried to book Robert Cray once before, Isaacson said they were thrilled to add the multi-Grammy winner and recent Blues Hall of Fame inductee to this year’s festival. During a recent telephone interview, Cray said that his drummer Tony Braunagel’s friendship with Benjamin enticed him to play the festival for the first time. Bruanagel also produced Trampled Under Foot’s “Wrong Side of the Blues,” released this spring.

Then there was Isaacson’s and Benjamin’s longtime love affair with Chicago blues.

“To me, those guys – Howlin’ Wolf, Muddy Waters, Koko Taylor – is where it all started,” said Isaacson, who plays piano with local band The Blues Prophets. “They’re like the Bach and Beethoven of blues.”

Artists like Waters and Wolf and later Buddy Guy exploded onto the music scene when they brought their Delta blues sound from the deep South to Chicago in the early half of the last century as part of the urban migrations. Almost instantly, harmonicas and guitars were attached to amplifiers and the beat caught up with the intensified pace of city life.

“Paul and I are just the conduits between the audience and the music,” Isaacson said . “We didn’t make any money that first show, and only about 1,500 people showed up. But we knew it would work.”

Since the one-day event in 1994, the North Atlantic Blues Festival has brought in acts like Koko Taylor, Keb Mo, Johnny Winter and Taj Mahal. It has expanded into two days of star cache and a club crawl night that features local musicians and shuts down Route 1.

“The artists love playing here,” Isaacson said. “The audiences are great, it’s beautiful and we promise them lobster.”

As Cray described blues festivals in general, it’s “a scene.” For this one, the backdrop of a scenic ocean view behind the Harbor Park stage immediately puts everyone in that no-worries frame of mind. Of course, you’re also hit with a multitude of aromas wafting from the food vendors on-site and a visual curiosity of trinkets being hocked.

But like all music festivals, people from all over Maine and even different parts of the country converge because they love the music. The person sitting on the blanket next to you may start the day as a stranger, but soon you’re trading stories about concerts and records just like old friends.

For Isaacson, who used to go to Chicago every spring and stay at a YMCA to hear blues musicians play in clubs, bringing artists to Rockland is part of what he does for a living as a promoter. But as a music lover who’s been playing in a band since he was 13, bringing artists to Maine and promoting music is a lifelong goal and passion.

Festival facts

Lineup:

Saturday, July 16, in Harbor Park

11 a.m. to noon: Nellie Tiger

12:15 to 1:15 p.m.: Eddy “The Chief” Clearwater

1:30 to 2:35 p.m.: Lil’ Ed & the Blues Imperials

2:50 to 4 p.m.: Billy Branch & the Sons of Blues

4:15 to 5:20 p.m.: Magic Slim & the Teardrops

5:35 to 7 p.m.: Brooks Family Blues Dynasty (Lonnie, Ronnie, Wayne)

Sunday, July 17, in Harbor Park

11 a.m. to noon: Trampled Under Foot

12:15 to 1:20 p.m.: James Armstrong

1:35 to 2:45 p.m.: Toni Lynn Washington

3:00 to 4:15 p.m.: Eric Bibb

4:30 to 6 p.m.: Robert Cray

FYI:

Gates open 9 a.m., music starts 11 a.m.

Rain or shine

No pets or coolers

No video recordings

No sun umbrellas or tents (rain umbrellas allowed if needed)

Bring lawn chair or blanket

Ticket info:

* Advance tickets sales end July 11; $25 per day / $50 weekend pass, including club crawl

* Tickets available online at www.northatlanticbluesfestival.com or at these outlets: Houston Tuttle, Rockland; HAV II, Camden; Gulf of Maine Books, Brunswick; Buck Dancers, Portland; Down Home Music, Fairfield; and Musicians 1st Choice, Augusta

* Tickets at the gate: $35 per day / $70 weekend pass, including club crawl

Children under 5, free; children 6-12 gate ticket only, $5