Data For January-June, 1922 Were Not Published. Beginning In 1934, Only 24 Industries Are Covered. The Silk Industry Was Excluded Due To Inadequate Data (See Source). Source: National Industrial Conference Board, For 1920-1933 Data: Wages, Hours, And Employment In The United States, 1914-1936; For 1934-1941 Data: Nicb Economic Record, March 28, 1940 And Following Issues; For 1942-1944: Nicb Management Record.
This NBER data series m08031 appears on the NBER website in Chapter 8 at http://www.nber.org/databases/macrohistory/contents/chapter08.html.
NBER Indicator: m08031
Release: NBER Macrohistory Database
National Bureau of Economic Research, Average Actual Hours of Work Per Week Per Wage Earner, Male, Semi-Skilled and Skilled, Twenty-Five Manufacturing Industries for United States [M08031USM065NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/M08031USM065NNBR/, October 8, 2015.