Kate Upton poses topless in this Terry Anderson shoot.

Kate Upton poses topless in this Terry Anderson shoot.

Kate Upton heads a top cast of models for the 2013 Sports Illustrated swimsuit issue. Actually, make that a topless cast of models. The iconic issue, dreamed up in 1964, has gotten racier over the years and now topless, and a few nude models fill its pages.

Despite the popularity of the issue, it took the magazine 33 years to figure out that it should exclusively feature an issue filled with models photographed in skimpy swimsuits in exotic locales.

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In 2006, the magazine published a “topless” cover featuring bare-breasted models Rachel Hunter, Veronica Varkova, Elle Macpherson, Rebecca Romijn, Daniela Pestova, Elsa Benitez, Carolyn Murphy and Yamila Diaz.

This issue caused such an uproar, subscribers have had the option since then of foregoing the issue.

“I just think the swimsuit edition degrades a magazine that generally does great work and is strong covering women’s sports,” writes Ed Sherman, who blogs about the sports media.

Last year, Irina Shayk, Brooklyn Decker and Cynthia Dicker were among 18 models who took off their bikini tops for the issue, which is getting racier every year.

This year, 39 models take off their tops and at least two models appear totally nude.

“Simply: The swimsuit edition is a blatant money grab, and SI knows it,” Sherman writes. “What I have found interesting through the years is how far SI will push the envelope in showing risque shots of the models.”

While many, but not all of the models pose topless, they have yet to reveal their private parts. All managed to keep themselves strategically covered. No doubt that took some staging on the part of SI’s staff.

Whether the peek-a-boo trend will continue is anyone’s guess. Avert your eyes if you must, but fashion keeps pushing the topless look.

Countless Hollywood celebrities have been photographed in public in loose free-flowing clothes without bras. Their full breasts have been captured by paparazzi and are regularly featured on the Web.

It may be that the United States is growing more cosmopolitan, or maybe it’s because of the hard economic times. But bare breasted models are increasingly turning up in upscale U.S. magazines like GQ and Esquire.

In Europe, it’s common to see topless women on billboards, not to mention most of the top European beaches and in top fashion magazines.

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Let’s face it, breasts are a sure attention-getter. And, the struggling media industry needs to do everything it can to hold onto readers.

Can Sports Illustrated be far behind? Maybe next year. Be sure to follow TheImproper on Twitter for all the latest fashion trends, clothed, or unclothed.