It took 20 years to do it, but the Irish Holy Trinity of Music is finally complete.

The Chieftains, The U2 and The Altan.

Ireland’s latest prodigy couldn’t have picked a better time to peak, as the popularity of Celtic music has reached an all-time high.

Even Midwesterners are capitalizing on Irish traditions, as bands like The Lash and The Drovers are building hefty fanbases.

But the seeds of Altan were planted well before the days of Celtic club shows on college campuses.

In 1979, Mair‚ad NŒ Mhaonaigh (pronounced “Ma-Raid Nee WEE-nee”) and her husband Frankie Kennedy made their recording debut with “Albert Fry.”

Preserving the distinctive fiddle style of her father, Francie Mooney, Mhaonaigh’s debut captured the spirit of Donegal, a northwestern Irish county that includes Loch Altan (the lake for which the group is named).

Donegal, a Gaelic-speaking community, borders a section of Scotland where several of Mhaonaigh’s ancestors went off to work and soak in the country’s musical flavor.

“There are many places in Ireland that have their own identities and traditions,” Mhaonaigh said in a press release. “Not all the band members are from Donegal, but we decided to focus in on what we know best, the place where I was born. That’s what we try and bring to the world.”

After recording “Ceol Aduaidh” (“Music From The North”) with her husband in 1983, Mhaonaigh didn’t re-emerge on record until Altan was formed in 1987.

The group has since spawned eight critically acclaimed records despite several line-up changes, including the tragic 1994 death of Kennedy due to bone cancer.

Altan’s latest, “Runaway Sunday,” was released by Virgin Records’ international label in 1997 and helped land the group a headlining slot at last summer’s Guinness Fleadh, along with The Chieftains, Wilco and Sinead O’Connor.

Mhaonaigh’s majestic voice is similar to O’Connor’s, but her fiddle skills have remained the hook in Altan’s creative lure.

“Runaway Sunday” is “The Joshua Tree” of the ’90s — a record that captures a country and captivates all others at the same time.

“We wanted to show all our colors this time around,” Mhaonaigh said. “I like the variety of textures on every track.”

The Lash, a Celtic ensemble from Lansing, Michigan, has a history quite different from Altan’s.

Members of prominent college rock bands from the area formed the group in spring of ’96 to play Irish tunes for a St. Patrick’s Day gig.

“We had no intentions of staying a band,” accordion player Michael Lynch said. “But the college kids just went crazy. We found out that Celtic music did quite well by accident.”

Modeling its sound after the radical ’80s Celtic punk band, The Pogues, The Lash took its name from the band’s 1985 album, “Run Sodomy and the Lash.”

“We knew Run Sodomy wouldn’t make a very good name,” Lynch joked.

The Lash has clinched on tight to its roots, combining the bass and drums of a traditional American rock fest with the banjo, accordion, mandolin and pennywhistle of an Irish picnic.

The group dubbed its sound Celtic Mayhem (think Swing Crew meets The Drovers).

“Basically, we’re a bunch of rock ‘n’ roll guys that started playing Irish music as opposed to folk musicians who started playing rock ‘n’ roll,” Lynch explained. “The texture of it is more traditional, but the way it feels is more like rock.”

Lynch, along with his bandmates, has long been a fan of Irish music and the genres that flourished from it, such as bluegrass and flamenco.

As a sales clerk at Elderly Instruments in Lansing, Lynch has seen the popularity of Irish music skyrocket in recent years. The store ships more Celtic instruments nationally than any other genre of instruments.

“Irish music has influenced so many different styles that I think people recognize it without really recognizing it,” Lynch said. “When we first started playing, people didn’t really know what to do. You could tell that they loved it and they were into it, but they didn’t know how to dance to it, and they weren’t sure why they were attracted to it. I attribute that to the music already being in them.”

College crowds are drawn to the group’s high-energy, often mosh-inducing, performances. Lynch also credits Celtic music’s reputation as “drinking music.”

“They seem to go hand-in-hand in a lot of ways,” he said.

“We love our Guinness. It’s kind of funny because when we first started playing around, we were drinking Guinness at all of the college bars and kids didn’t know what it was. In Lansing, in two of the bars we play at, now it’s their No. 1 seller.”

The Lash even flirted with a promotional deal with Guinness, who has been a leader in the Celtic resurgence with its annual Fleadh (pronounced “flah” and Gaelic for “festival”), but a deal was never finalized.

On The Lash’s debut live record, “Celtic Mayhem,” jigs such as “Bottom Of A Bottle” and “Whiskey Made Me Do It” reflect the group’s witty attitude toward Ireland’s most celebrated pastime.

“Whiskey,” a clever ode to beer goggles, boasts the chorus, “I’ve done a lot of drinking since I walked through the door/ But one more look at that ugly queen and I had to have 10 more.”

But the record is not all giggles, and Lynch and cohorts hope listeners will realize the roots buried behind The Lash’s vigorous outer layer.

“We wanted the first album just to be a buzz maker,” Lynch said. “And we thought the best way to build a buzz was to try to capture the show on tape as best as we could. The second album is going to be a little more serious.”

In its two years of mayhem, The Lash has shared the stage with such diverse acts as rockers 7 Mary 3 and Irish folk legends The Clancy Brothers.

“One nice thing about this band is that I can invite my grandfather and my nephew and they’re both going to walk away with something they like.”

Altan plays two shows at the Maintenance Shop tonight at 7:30 and 10 p.m. Tickets are $13, $10 for students.

The Lash plays Saturday at the Maintenance Shop at 9 p.m. with Chamberlain. Tickets are $5, $4 for students.