In the past the census enumerator has been depended on to supply information as to the number of blind persons. The enumeration at its best has been incomplete and often incorrect. This was definitely proved in the National Health Survey conducted by the United States Public Health Service from 1935 to 1936.1
During the summer of 1930, the blind in a small Connecticut area were enumerated, one purpose being a comparison of results with those of the federal census. After thorough search it was found that not only was this special enumeration incomplete, but the Census Bureau had enumerated only 49 per cent of the blind in that area.
In the 1930 Census Bureau report, 626 blind persons were recorded for the State of Maine; yet in this State there were 1,268 persons receiving aid to the blind in April 1938, and it would not seem likely
RIEMER HBC. TOPOGRAPHIC AND ETIOLOGIC STUDY OF 1,176 INDIGENT BLIND PERSONS IN MASSACHUSETTSA BASIS FOR PREVENTION OF BLINDNESS. Arch Ophthalmol. 1944;32(4):304–307. doi:10.1001/archopht.1944.00890100062009