And why today is a dynamite excuse to buy it.

Photo courtesy of Haspel

Seersucker: It's a staple of the Southern gentleman's closet, worn by everyone from Gregory Peck in To Kill a Mockingbird to Presidents Ronald Reagan and George H.W. Bush. These days, it's hard to imagine seersucker being worn by anyone besides the most dapper of dressers, but the fabric, which was first popularized in colonial India, was used in the early 20thcentury in America as a uniform for laborers working in hot conditions, like, say, a factory in New Orleans.

Joseph Haspel Sr. owned a New Orleans textile factory that churned out military-style suits and overalls, and in 1909, he took the lightweight, puckered fabric and made the first seersucker suit—a tailored, but breathable option that was cool enough (and stylish enough) for hot New Orleans days.

"Because of my great-grandfather, seersucker suits are seen as the way a proper gentleman could and should be dressed," says Laurie Haspel, who serves as president and CEO of Haspel, which is now based in Baton Rouge. "But the seersucker suit was born out of necessity. It's not just fashionable; it's about function too."

In the early 1900s, U.S. senators took a cue from their Southern contingent and wore the seersucker suits to fight off the stifling heat in their un-air-conditioned chamber. While air-conditioning kicked that tradition to the curb in the ‘50s, in 1996, Mississippi Senator Trent Lott designated a Thursday in June "Seersucker Thursday," encouraging his fellow senators to ditch the dark suits for the summery alternative. That tradition, too, fell to the wayside for a couple of years, but made a full-on comeback in 2014 when now-Senator Bill Cassidy, who is from Louisiana, introduced National Seersucker in the House of Representatives. This year, they'll be celebrating National Seersucker Day on June 7.

"While the origins of the holiday started on the halls of Washington, essentially, that was just the fire we needed to send off a fun celebration across the country," says Haspel. "Our clothes are meant to be worn for a good time. We want people to have fun and drink to this wonderful fabric and this wonderful company that my grandfather started back in 1909."

Don't have seersucker of your own? Haspel is the original source for men's options, while Arkansas-based designer Lauren James offers plenty of pretty options for the ladies. And Vineyard Vines has everybody, including your little ones, covered.

WATCH: Stylish Items Every Southern Woman Needs In Her Closet

Celebrate the occasion on June 7 by donning your seersucker finest, and join the party on Instagram using the hashtag "#NowYouSeerMe" and tagging @haspelclothing.