The statistics presented in this bulletin showing workers classified by major occupation groups and class of worker are limited to employed workers, that is, persons 14 years old and over who were actually at work or who had a job in the week of March 2.1 to 30, 1940.
The occupation statistics presented in this bulletin are in terms of 10 major groupings of the 451 specific occupation titles of the 1940 classification system used by the Bureau of the Census. It may be noted that the occupations Farmers (owners and tenants) and Farm managers are included in the major occupation group Proprietors, managers, and officials; and that the occupations Farm laborers (wage workers) and farm foremen and Farm laborers (unpaid family workers) are included in the major occupation group Laborers.

On the basis of their employment status or activity during the week of March 24 to 30, 1940, all persons 14 years old and over were classified into two large groups: (a) Persons in the labor force, including those employed (at work or with a job, except on public emergency work), those on public emergency work, and those seeking work; and (b) persons not in the labor force, including those engaged in own home housework, those in school, those unable to work, inmates of institutions, other persons not in the labor force, and those whose employment status was not reported.
In the interpretation of the data for persons on public emergency work, allowance must be made for the misclassification in the census returns of some public emergency workers, as a result of which the number of such workers is considerably understated.