Series Is Presented Here As Two Variables--(1)--Original Data, 1870-1924 (2)--Original Data, 1924-1950. Source: Railway Age, Monthly Reports Of Carriers And Equipment Builders.
This NBER data series q06027a appears on the NBER website in Chapter 6 at http://www.nber.org/databases/macrohistory/contents/chapter06.html.
NBER Indicator: q06027a
Release: NBER Macrohistory Database
National Bureau of Economic Research, Orders For Freight Cars Placed By American Railroads For Domestic Use for United States [Q0627AUSQ559NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/Q0627AUSQ559NNBR/, July 4, 2015.