Data Through May 1923 Include S. And T. Companies And Were Computed By NBER. Data Beginning June 1923 Excludes Switching And Terminal Companies. Source: Interstate Commerce Commission, Wage Statistics.
This NBER data series m08178 appears on the NBER website in Chapter 8 at http://www.nber.org/databases/macrohistory/contents/chapter08.html.
NBER Indicator: m08178
Release: NBER Macrohistory Database
National Bureau of Economic Research, Straight Time Hourly Earnings, First Class Railroads for United States [M08178USM259NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/M08178USM259NNBR/, October 7, 2015.