Senators Dress Up for Seersucker Thursday

— -- One day each year, visitors to the Senate can see many lawmakers and their staffers wearing lightweight, puckered seersucker suits in pinks and blues, a look most commonly associated with Southern gentlemen and mint juleps.

It’s become an annual Senate affair: “Seersucker Thursday,” when regulars get together to pay tribute to the fabric’s storied Capitol Hill history and have a little bit of fun.

This year, Sen. Bill Cassidy of Louisiana organized the event, complete with social media props like a seersucker picture frame and a cardboard cutout of a seersucker suit for those who missed the style memo and wanted to post pictures under the hashtag #SeersuckerSelfie.

“It's kinda fun, it's bipartisan, it's something that people can participate in and kind of see each other and smile and thumbs up -- it doesn't matter anything else that's going on,” Cassidy told ABC News.

It all started with Sen. Trent Lott, who in 1996 decided to start the tradition of posing with his colleagues in seersucker (and white buck shoes, of course) as a way to prove that, in his words, “the Senate isn’t just a bunch of dour folks wearing dark suits and -- in the case of men -- red or blue ties.”

The tradition also has its roots in Capitol Hill history. In the early 20th century, lawmakers would routinely switch to seersucker in the summer months before Congress had air conditioning.

Lott's event began as an all-men’s affair, but in 2004, Sen. Dianne Feinstein of California decided she wanted to get the women of the Senate in on the act also. However, most of her female colleagues didn’t own seersucker suits, so Feinstein got all of their measurements and had bespoke suits made as gifts.

During this year’s photo op, Sen. Susan Collins of Maine was wearing the suit Feinstein gave her.

“It’s that old!” she joked.

“I have to say, I understand why Southerners are in love with seersucker,” Collins continued. “Because it really does breathe, it's cool, it doesn't wrinkle easily. And it is great fabric for the South. It's not something you're going to see me in the coast of Maine very often.”