GoTopless Day always falls at the Sunday closest to Women's Equality Day, Aug 26. It is indeed on Aug 26, 1920 that women earned their right to vote on the basis of Gender Equality. In 1971, the US Congress has made Aug 26 into a nationally recognized date and named it "Women's Equality Day". The president of the United States is summoned to commemorate this date each year.
It is only logical that GoTopless Day protests (or celebrations depending on the legal status of your city) would fall around Women's Equality Day since the right to go topless for women is based on gender equality as their right to vote once was.
"As long as men are allowed to be topless in public, women should have the same constitutional right. Or else, men should have to wear something to hide their chests" Rael, founder of GoTopless.org and spiritual leader of the Raelian Movement (rael.org)