Seersucker Thursday is annual tradition in the United States Congress in which Senators don the lightweight, striped, summer-friendly fabric seersucker, in the spirit of traditional Southern clothes, on usually the second or third Thursday of June.
The tradition was started by Republican Senator Trent Lott of Mississippi in 1996 who wanted to "bring a little Southern charm to the Capitol" to remind the Senate of how Senators dressed before the advent of air conditioning in the 1950s. The cotton weave, which originated in western India, became a signature look of the United States in the early 20th century because its light weight and pre-rumpled surface made it ideal for the oppressive humidity of summer. 
While this tradition is an annual event, it is common to see Congressional staffers don seersucker suits on Thursdays throughout the year.
History of the seersucker suit 
Seersucker weave was introduced to the American south, probably through British colonial trade, sometime in the second half of the 19th century.
In 1907 a New Orleans tailor made the first seersucker suit to make the summer wear more comfortable. He called the light weight, pale blue and white striped rumpled cotton fabric "seersucker" from the Persian words for "milk" and "sugar". The suits became widely popular because they retained their fashionably good looks even despite multiple washings that are necessary during the summer. In the 1920s seersucker suits were adopted by the wealthy Northerners who vacationed in the South and from there became near universal in Northeastern cities in the 1930s. Well into the 20th century, on the first warm days of spring, journalists would report on the seasonal transition in the poorly ventilated Senate chamber.
Gregory Peck famously wore a seersucker suit in the movie To Kill a Mockingbird, creating a cliché of how small town Southern lawyers dressed invoked by later actors such as Andy Griffith. The image of a bow-tied, seersucker-suited young man in a boater hat is likewise a cliche image of a recent graduate of elite Northeastern colleges.
History of Seersucker Thursday 
In 1996 Senator Trent Lott decided to bring the tradition back. His goal was to show that "the Senate isn’t just a bunch of dour folks wearing dark suits and—in the case of men—red or blue ties". In 2004, Senator Dianne Feinstein decided to increase participation by encouraging women senators to follow the tradition. The following year 11 of the 14 women senators appeared on Seersucker Thursday in outfits received as gifts from Feinstein.
As of June 27, 2012, Seersucker Thursday was announced to be discontinued.
- Seersucker Thursday. US Senate. Accessed 17 July 2009.
- Bedard, Paul (13 June 2007). "Suckers for Seersucker". US News and World Report. Retrieved 17 July 2009.
- Jaffe, Matthew (21 June 2007). "Seersucker-Suited Senators Dress for Success". ABCnews. Retrieved 17 July 2009.