From the website: http://www.laundrylist.org/programs/education/70-national-hanging-out-day
"Every year, on April 19th, Project Laundry List joins together with hundreds of organizations from around the country to educate communities about energy consumption. National Hanging Out Day was created to demonstrate how it is possible to save money and energy by using a clothesline.
For many people, hanging out clothes is therapeutic work. It is the only time during the week that some folks can slow down to feel the wind and listen to the birds. Consistent use of clotheslines or drying racks can save the average household much more than a hundred dollars every year in energy bills. Clothes last longer and smell better, too".