Should it be Arkansas' or Arkansas's? That is the question. (AP) (NPR)

The final possessive "s" is seen as necessary because of the current pronunciation of the state's name, and will be debated in the Arkansas state legislature.

"After Arkansas became a state, confusion remained on its spelling and its pronunciation, as many maps from the time spelled it without its final "s." A resolution by the Legislature in 1881 formalized its current spelling and pronunciation, making its final "s" silent."

I found this story originally on Language Log, the blog of UPenn phonetician, who has lots of cool items.