Is the Holy Grail of rock posters from a Buddy Holly show in Mankato?

It could be the Holy Grail of rock posters – and it has a Minnesota connection.

No, it's not related to Bob Dylan or Prince. It's from the Winter Dance Party 1959, the fateful Upper Midwest tour that took the lives of Buddy Holly, Ritchie Valens and the Big Bopper in a plane crash in Clear Lake, Iowa.

The tour played 11 cities before the tragedy on Feb. 3. One was Mankato, the Kato Ballroom.

Heritage Auctions is selling a poster of the Jan. 25, 1959 concert in Mankato.

"People didn't save much in the '60s and they saved nothing in the '50s," said Pete Howard, a longtime poster collector who is now Heritage's consignment director of music memorabilia. "There is only one from Mankato. This is as rare as anything gets.

"This is the Holy Grail of rock posters because this was the first rock 'n' roll tragedy. It was an iconic shift in pop culture and society."

And there are only three known Winter Dance Party 1959 posters from before the crash – and two from after, according to Howard.

A poster from the Moorhead, Minn., show – the one Holly and others were flying to – sold privately for $175,000. Howard thinks that's a record for the sale of a rock poster.

The Winter Dance Party also performed in St. Paul, Montevideo and Duluth (Bob Zimmerman, aka Bob Dylan, was in the audience there) as well as cities in Wisconsin and Iowa.

The Mankato poster was owned by Janice Bucek Eggers, who, as a rural Minnesota teen, grabbed it off a Kato Ballroom wall when she left the concert. She sold the poster in 2006 and provided a provenance.

The buyer – and current owner – had it "expertly touched up," Howard said, such as having the scratches painted.

The poster is on auction through Saturday at HA.com/7217. The current bid is $22,000.