American Routes, the New Orleans-based public radio music show that’s heard by 1 million listeners via 275 stations throughout the nation, is celebrating its 15th anniversary Friday, April 19, at Rock ’n’ Bowl.

Despite American Routes’ journeys to Memphis, Detroit, Chicago and other musical destinations, the program’s heart and soul remains on the Gulf Coast.

True to form, Friday’s anniversary concert lineup features classic New Orleans rhythm-and-blues performers Irma Thomas, Robert “Barefootin’ ” Parker and Walter “Wolfman” Washington, more local talent via the Treme Brass Band, Ivan Neville and Jon Cleary plus Cajun-rock band Lost Bayou Ramblers.

“It was important that we have Louisiana music and musicians in the concert and make it substantially south Louisianan,” Nick Spitzer, American Routes host and producer said this week.

“I wish we had Baton Rouge in there,” he added, “but I had to have New Orleans traditional jazz and some of the heroes of New Orleans music, from R&B to soul to funk.”

American Routes’ 15th anniversary concert follows fifth and 10th anniversary events.

“Every five years we feel like it’s time to thank the staff and remind the network listeners that we’ve been around for a while,” Spitzer said.

Spitzer’s sees American Routes, a program that seamlessly blends music and interviews, as a sort of non-fiction Prairie Home Companion.

“Prairie Home Companion references the upper Midwest, Minnesota, Wisconsin, Iowa, the Dakotas,” he said. ??We represent the Gulf South particularly and stay mostly within the borders of Louisiana.

“A big difference between American Routes and Prairie Home Companion is that the people and places in our show are real. In this part of the world, truth is stranger and more entertaining than fiction. But I do occasionally say, ‘That’s the news from Lake Pontchartrain.’ ”

Spitzer, a professor of anthropology and American studies at Tulane University and a former folklife specialist at the Smithsonian Institution, didn’t expect American Routes to last as long as it has. It all began with his request to the Corporation for Public Broadcasting for $90,000 to test an eclectic radio program based in American music and culture and emphasizing the Gulf South.

“They liked the demo so much that they gave us three times the amount of money we requested, almost $300,000, and said, ‘Produce the show and see how it goes.’ They didn’t force us to do the usual focus-group work. I think they thought we were ready to do something.”

American Routes launched with just seven stations aboard. The seven quickly became 40 and then 60.

“It’s continually risen over the years,” Spitzer said. “Hurricane Katrina gave us a huge boost because so many people became interested in the region.”

Although American Routes is more widely heard than ever, the state and federal funding that has helped Spitzer and his small staff produce the show through the years has been drastically cut, to the tune of hundreds of thousands of dollars in the past four years.

“It’s a sweet and sad moment in a way,” Spitzer said of the show’s 15th anniversary. “The concert’s gonna be a blast but we need to find a major corporate underwriter, hopefully from Louisiana.”

For financial and other reasons, Spitzer, 62, is not sure if there will be a 25th anniversary for American Routes.

“One of the good things about radio is that, as long as you remain reasonably coherent and somebody wants to listen, you can do a show,” he said. “You don’t have to be beautiful, like television.

“But the audience expects a certain depth from us. It’s not just about entertaining or reading a newscast. I’m not going to promise we’ll be here for a 25th anniversary, but I can say that we will attempt to be vibrant for a number of years into the future.”