Wear White After Labor Day?

I was in the company of two girl friends the other day. They both were wearing white slacks. They made the comment that they thought they'd get another day's wear from the white slacks because they couldn't wear white after Labor Day. I had no idea that women still followed that old rule. White is white, there is a "winter white". Is that less white than "summer white"? The difference is in the fabric not the color. What my friends should have said is "I can't wear white cotton after Labor Day". Actually, summer isn't officially over until Fall begins. So, I'd say wear your white and your cotton until the temperature drops. That may not happen for several weeks if we're lucky.