Geographical distribution of insanity in America: evidence for an urban factor.

The geographic distribution of insanity and schizophrenia in the United States is examined for 9 separate years between 1880 and 1963. A concentration of these conditions in Northeastern and Pacific Coast States was remarkably consistent over the 83 years. States with a high prevalence rate had approximately three times more insanity and schizophrenia than those with a low prevalence rate. There is a direct regional correlation of insanity/schizophrenia with urbanization, which is consistent with previous studies. There is also a direct regional correlation of schizophrenia with socioeconomic status, which contradicts previous studies carried out in large cities in which the schizophrenic rates were inversely correlated with socioeconomic status. The apparent discrepancy can be explained by postulating that the direct regional correlations are due to correlations of urbanization and socioeconomic status (cities have higher mean incomes than rural areas) whereas, within a particular city, schizophrenia is more prevalent among lower socioeconomic groups because of drift and other factors. Social, stress and crowding, genetic, and biological factors are discussed as possible explanations for the urban factor associated with insanity/schizophrenia.