The early censuses were extremely unreliable.
By this means the attention of the office could be concentrated on a small number of subjects rather than distributed over the long list treated in the volumes of the tenth and eleventh censuses.
Walker, superintendent of the censuses of 1870 and 1880, the remarkable fact that such reduction coincided with a cause that was regarded as certain to quicken the increase of population, viz, the introduction of a vast body of fresh peasant blood from Europe, afforded proof that in this matter of population morals are far more potent than physical causes.
Since 1850, however, provision has been made on an ample scale for their collection, although the constant modifications of the schedules under which the statistics were arranged makes very difficult comparisons of the latest with the earlier censuses.
In 1905 was taken the first of a new series of special decennial censuses of manufactures, in which only true factoriesthat is, establishments producing standardized products intended for the general marketwere included, and mere neighborhood (local) establishments of the hand trades were excluded.