According to a Sept 12, 1926 NYT article, the chestnut blight was believed to have been brought into Nassau County, Long Island in the late 1800's by chestnut trees imported from Japan where the fungus originated. The Japanese trees were resistant. The fungus was first noted in 1904 on an American Chestnut at the NY Botanical Gardens.
http://timesmachine.nytimes.com/timesmac...972862077258563