how long can ribbon snakes get?

In the past few months I have seen a large, what I think to be, western ribbon snake. Well today cleaning out my backyard I found a perfect shed, that standing next to me was to my nose(I am 5'5). Do ribbon snakes get that long or could it be something else? It was all black with a yellow stripe down the side and I can't find any other snakes native to louisiana with that pattern.

Ribbon snakes do not get that big....but eastern garter snakes can hit 4 ft. You must also consider that a snake's skin is elongated when it sheds. For example, a 3 ft snake's shed may be 4 ft because it was streched.

Actually, I spotted an eastern garter in my back yard over the weekend. From my experience, they tend to move around a bit more when the weather starts to cool.