ROSEMONT, Ill. (CBS) — Avid collectors of sports memorabilia are descending on the Chicago-area starting this afternoon for the world’s biggest sports show.

As WBBM Newsradio 780’s Regine Schlesinger reports, a $3 million Mickey Mantle card collection is among the highlights.

LISTEN: Newsradio 780’s Regine Schlesinger reports

Over the past 20 years, sports collecting has exploded as a hobby and business. At the National Sports Collectors Convention in Rosemont, J.P. Cohen with California auction house, Memory Lane, is showing off the Mantle collection on loan from a private collector.

The collection includes one piece, Mantle’s 1951 rookie card, worth $1 million by itself.

“That is considered the holy grail of post-war cards,” Cohen said. “We call the Honus Wagner card the holy grail of pre-war cards.”

Cohen says this show is the biggest event of the year for sports collectors.

“Anything that exists in sports collectibles, it’ll be at the show,” Cohen said. If you come to the show and you don’t find it, that means it doesn’t exist. It takes some people two, three days just to walk the show. That’s how big it is.”

The National Sports Collectors convention runs through Sunday at the Donald E. Stephens convention center in Rosemont.

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