It’s interesting to note that there is claimed “Parkinson Disease belt”:
“Our study indicates that there is a ‘Parkinson disease belt’ with high prevalence and incidence of Parkinson disease involving the Midwest and Northeast regions. This nonrandom disease distribution argues strongly for an environmental influence on the pathogenesis of Parkinson disease.”
“Our study indicates that there is a ‘Parkinson disease belt’ with high prevalence and incidence of Parkinson disease involving the Midwest and Northeast regions. This nonrandom disease distribution argues strongly for an environmental influence on the pathogenesis of Parkinson disease.”
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2865395/