How does this happen?? Just one shoe?

I am always so baffled as I bicycle along the highways and byways and back roads and main roads at this one strange thing: All across the USA I so often see along side of the road JUST ONE SHOE! How in the world does this happen time and time again? How do these single soles get out there on the road or along the berms? It is a total mystery to me. Just one - never a pair. Do people toss these out the windows of their vehicles? Do they fall off the back ends of trucks? Do kids roll down windows and throw them out? When I rode across country on my first cross-country bike ride back in 2001 I wish I would have counted the times I saw JUST ONE shoe or boot along the way out there on the road! This photo was taken last summer when I was cycling up some mountain pass out there in the Colorado Rockies. One lonely boot all by itself. Whose was it? I'll never know. I was on a bike ride today and sure enough I saw a ONE SHOE-R on the side of the road. If you are curious as to what I saw the MOST of on the sides of the roads during my first cross country trip 3,000 plus miles: Here they are #1 BUNGIE CORDS, #2 NUTS & BOLTS, #3 SINGLE SHOES and #4 --- --- ready for this --- UNDERWEAR!! Only in America.