MANKATO — KMSU Radio host Mark Halverson has done the math. If the bankruptcy attorney by day billed the campus radio station roughly his hourly rate, Halverson estimates he’s donated $1.7 million of his time since his first show aired on AM radio in the early 1970s.

“I think of other things I could do with my time,” Halverson said in the station’s studio on a recent Sunday night, as he prepared for a live broadcast of his “Blues Before Monday” program, which entered its 20th year in February. “And sometimes I wonder if anyone’s listening. But as far as blues programs go — and I pay attention to other shows — I’d say this one is pretty good.”

Minutes before air time, Halverson sifted through a knapsack stuffed with a portable library of blues albums and compact discs, fine-tuning the show’s play list. A selection of blues harmonica tracks were chosen for a segment, which Halverson dedicated to his friend, local harmonica wizard and City Mouse founder Billy Steiner.

“Mark does a great job up there,” said Steiner, who’s known Halverson since the early 1970s. “He’s an extremely intelligent guy, and it’s a really good thing for us to have here, someone who’s so passionate about the blues. And I love it, too, because he gets his political licks in.”

Equipped with liberal ethos, a wry wit and mastery of blues vernacular, Halverson — “Marconi M. Milquetoast” and “Marky Moondog” are often his disc jockey monikers — produces nearly seven hours of blues programming each week on a volunteer basis, including his shows “Blues Break,” “Blues Before Monday” and “Blue Monday.”

“Mark’s a true blues aficionado,” said fellow KMSU volunteer Gary Campbell, Halverson’s childhood friend and former “Blues Before Monday” partner. “He has an incredible blues tenacity. He probably has the largest collection of blues festival T-shirts in the Midwest. He just really enjoys being a part of the blues community.”

A 1969 graduate of St. Peter High School, Halverson, like many of his peers, fell prey to the music’s hypnotic lure after encountering the blues via the burgeoning psychedelic rock ’n’ roll scene. And he hasn’t been the same since.

“I came of age musically just as the ’60s started to hit this area, which was the late ’60s,” he said. “We were listening to the Stones, the Beatles, Hendrix, and Muddy Waters was just starting to cross over into rock ’n’ roll. That opened our eyes up to the heartfelt, soulful nature of the blues. But there were no blues shows on FM — there wasn’t even FM. You had to catch a skipping signal on AM somewhere out in Arkansas late at night.”

Halverson’s association with community radio dates back to the early 1970s, when as a political science major at then-Mankato State University he briefly hosted a music program on the station’s AM component.

“When I was speaker (of the student senate), KMSU used to be owned by the students back then,” said Halverson, who served as a student senator for three years. “One summer, the administration, when most of us weren’t around to squawk about it, moved it to the administrative side of the university. We referred to it as stealing the radio station.”

Halverson has since witnessed many changes at the station — equal parts technological, musical, financial and philosophical — since the inception of “Blues Before Monday” in February 1991.

“The station was a lot bigger then,” he said. “We used to have eight full-time staff members. Now we have two. I’m not really happy about that, but there are financial issues everywhere, so it’s understandable.”

“When I started coming here, CDs were just starting to come along,” he said. “First it was vinyl, then tapes and compact discs. Now, it’s gotten to the point where people expect you to download an MP3 off the Internet.”

What hasn’t been altered with the modern times is Halverson’s unrelenting affection for all facets of the blues. However, unlike the typical blues scholar, he’s wary of intellectualizing the murky elements behind the music’s evolution.

“I don’t think you should over analyze this stuff,” said Halverson, a charter member of Mississippi and Minnesota blues societies. “For example, where do you draw the line between blues and jazz? There’s a theory that the blues is the root of all American music, and I’ve seen people actually chart that out. But it all depends on where you start, where you draw the line, how you turn the tree.”

Halverson paused when asked what kept him motivated to bring the sounds of the blues to an untold number of listeners each week. He possesses a vast collection of guitars, bass and Hammond B3 organs that remain largely ignored in proportion to his disc jockeying activities. There are also train rails to ride, Mankato MoonDogs baseball games to attend, and lest he forgets, that pesky day job as an attorney.

“If I practiced those instruments seven hours a week,” he said, “I’d have to be proficient by now, even if I don’t have much musical talent. ... But I’ll keep doing the show as long as there’s a forum. I guess I just love the music. That’s the bottom line.”