The Cadillac [MI] News reports on the incidence of Social Security disability receipt within the state of Michigan. Not surprisingly, to me at least, disability hits hardest in poorer rural areas with older populations. Many of the healthy young people leave those areas to take jobs where they can find them. The population left behind is older and sicker. Of course, a higher percentage of the remaining population files disability claims.
By the way, what I've seen in North Carolina is that these poorer rural areas eventually generate fewer disability claims -- once the local population is greatly diminished, as it surely will be over time, since there aren't jobs to be had. The older, sicker population just dies off.