The Cool Thing to Wear to the Big Game? Something Old.

The team store: A glorified souvenir shop at stadiums and arenas, where sports fans shop for official jerseys, snapback hats and a variety of magnets and key chains.

Also: rather passé.

“That is very out,” said Lily Shimbashi of Sportsish, a pop-culture newsletter and podcast aimed to female sports fans. “No one is buying apparel from the teams anymore, because it’s boring. It’s ugly.”

For more and more fans, official game-day apparel has been replaced by less official, trendier gear sold online. This shift has created a particular frenzy around vintage sportswear, like graphic tees circa 2001 — the Mets opening day or the Florida A&M University homecoming — or colorful, crispy N.B.A. Starter jackets.

According to Google Trends, search interest in vintage N.F.L. items has nearly quadrupled in the last year, particularly in Missouri, home of the Kansas City Chiefs. The day after it was determined that Kansas City would play the San Francisco 49ers in the Super Bowl, eBay searches for vintage 49ers T-shirts rose by more than 400 percent in the United States and Canada.

But this is not just about the Super Bowl: In the last six months, searches on Etsy for vintage football jerseys, regardless of the team, increased by 62 percent, compared to the same time period last year.