Social Securities Paid By Employers Are Not Included; Pensions, Compensation For Injury And Relief Payments Are Likewise Excluded From This Series. Source: For 1919-1938: Simon Kuznets, National Income And Its Composition (1941) Volume I, Table 62, Pp.332-323; For 1939: The Data Were Extrapolated With The Aid Of The Department Of Commerce Data From Table 15 Of "National Income And National Product In 1943" By Milton Gilbert And George Jaszi; And Survey Of Current Business, April 1944, P.15.
This NBER data series a08181 appears on the NBER website in Chapter 8 at http://www.nber.org/databases/macrohistory/contents/chapter08.html.
NBER Indicator: a08181
Release: NBER Macrohistory Database
National Bureau of Economic Research, Wages and Salaries, Total for United States [A08181USA144NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/A08181USA144NNBR, February 8, 2016.