Data For July 1930-1932 Were Computed By NBER, And The Monthly Figures For July 1924-1930 Were Checked Against Nicb Quarterly Figures. Source: Computed By The National Industrial Conference Board From Data In Icc "Wage Statistics."
This NBER data series m08037 appears on the NBER website in Chapter 8 at http://www.nber.org/databases/macrohistory/contents/chapter08.html.
NBER Indicator: m08037
Release: NBER Macrohistory Database
National Bureau of Economic Research, Average Hours of Work Per Week, Class I Railroad Employees, Unskilled Labor for United States [M08037USM065NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/M08037USM065NNBR/, August 3, 2015.