The latest issue of the highly anticipated Sports Illustrated Swimsuit Edition was released this week with Kate Upton gracing the cover. The 19-year-old American model wears a red-string bikini and shows off her body on the 2012 SI cover.

The popular Swimsuit Edition has featured models, actresses, singers and sports stars for more than fifty years. The magazine often helps propel models to supermodel status. Many of the past cover girls, including Tyra Banks, Christine Brinkley and Cheryl Tiegs, became supermodels and sex symbols after gracing the magazine's cover.

The Sports Illustrated Swimsuit edition is often credited with making the bikini, invented in 1964, a legitimate piece of swimwear. However, many of the Sports Illustrated issues from the 60s, 70s and 80s feature models wearing one-piece bathing suits, rather than bikinis.

Take a look at photos of the 20 hottest covers of all time. The hottest Sports Illustrated Swimsuit Editions feature Kate Upton, Cheryl Tiegs, Christine Brinkley, Paulina Porizkova, Elle Macpherson, Vendela Kirsebom, Tyra Banks, Marisa Miller, Bar Refaeli, Brooklyn Decker, Irina Shayk, and more.

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