From 1932, Smithing And Terminal Companies Are Not Included Within The Dataset. Source: Interstate Commerce Commission Wage Statistics
This NBER data series m08174 appears on the NBER website in Chapter 8 at http://www.nber.org/databases/macrohistory/contents/chapter08.html.
NBER Indicator: m08174
Release: NBER Macrohistory Database
National Bureau of Economic Research, Aggregate Compensation on an Hourly Basis, Railway Workers for the United States [M08174USM144NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/M08174USM144NNBR, April 28, 2016.