Data Were Computed From Wage Statistics By NBER, By Dividing Total Compensation For A Month (On An Hourly Basis) By The Number Of Employees At The Middle Of The Month. Source: Interstate Commerce Commission, Bureau Of Statistics, Wage Statistics Of Class I Steam Railroads In The United States, July 1921 And Successive Issues, P.4 Of Each.
This NBER data series m08047 appears on the NBER website in Chapter 8 at http://www.nber.org/databases/macrohistory/contents/chapter08.html.
NBER Indicator: m08047
Release: NBER Macrohistory Database
National Bureau of Economic Research, Average Monthly Wages, Professional Clerical and General Employees of First Class Steam Railroads for United States [M08047USM052NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/M08047USM052NNBR/, October 6, 2015.