Robert Earl Keen to play The National on Tuesday

While people all over the world are pausing to recognize the 20th anniversary of the fall of the Berlin Wall, Texas singer-songwriter Robert Earl Keen's rabid fan base is celebrating an event that also took place two decades ago.

In 1989, Keen penned "The Road Goes on Forever" for his "West Textures" release on Sugar Hill Records.

The raucous tale of diner waitress Sherry and drug-dealing Sonny features the now famed chorus: "The road goes on forever . . . and the party never ends."

The song is a permanent entry on Keen's set list, and its chorus has found its way onto more than one tombstone. It also was the final words of a Texas death-row inmate.

As part of the yearlong 20th birthday party, Keen, 53, published "The Road Goes on Forever and the Music Never Ends," which contains, among other things, the lyrics and background notes for 24 of his favorite compositions.

A film documenting the improbable impact the song has had on Keen's fans is also in the works.

Writing a song that would take on a 20-year-and-counting life of its own was not Keen's goal when he put the finishing touches on "The Road Goes on Forever."

"I had no clue how much it would work and what it would do," Keen said over the phone from a tour bus in Illinois. "I enjoyed writing the song, but the short answer would be, I was just relieved to have a song to finish the record with."

At the same time that "The Road Goes on Forever" legacy is being honored, Keen is promoting the release of "The Rose Hotel," his first studio album in four years.

The album's tracks -- which fit under the large Americana music umbrella include Keen's typical lyrically rich alt-country character sketches and quirky tales along with covers of tunes from Townes Van Zandt and Greg Brown.

Keen gives big props to production genius Lloyd Maines (father of Dixie Chicks' Natalie Maines) for the album's terrific sound.

"He's the best people-person I've ever known. He could be the head of the United Nations, and everyone would be able to communicate their point in very short order," Keen said. "No one ever feels slighted or insulted. He always gets the best out of people."

Actor-singer Billy Bob Thornton makes a cameo appearance on "The Rose Hotel," adding backup vocals to the funny "10,000 Chinese Walk Into a Bar," a result of a chance encounter Keen's road manager had with Thornton in Austin, Texas.

Turns out that Thornton is a big fan.

"I usually don't call stars because I don't know what to say," Keen said. "But I'm also a fan of his, so I called him. We really hit it off. We have some mutual friends, and we talked for a long time. That next day, I was working on '10,000 Chinese.'"

Thornton is part of a Robert Earl Keen fan club that has been steadily building and evolving during the past 20 years or so.

While Keen's early days were spent as a solo singer-songwriter in rooms more suited for serious listening than hollering and fist-thumping, he eventually hired a few band mates. After that, Keen added the enthusiastic and demonstrative college male community to his audience.

"At that point, that thing that Malcolm Gladwell talks about, the tipping point occurred. Everybody showed up, and half of them were fraternity guys," he said. "I didn't chase after them -- it just happened. I was never in a fraternity, so I didn't know what it was. They filled up a lot of seats for at least four or five years, and they chased off the old hippies that watched me.

"Then the frat boys kind of dwindled away. Now it's this huge mix, . . . everyone from older frat guys to little-bitty kids and grandmas. I used to make this joke that I was the Milton Bradley game of entertainment, because I was designed for everyone from 8 to 80."