Data For 1889-1890 Were Computed From Freight Earnings And Ton-Mile Data Of Individual Railroad Reports. NBER Checked Data By Dividing Figures For Freight Earnings By Ton-Miles For The Group Of Six Railroads. Source: Poor'S Manual Of Railroads, 1888, Pp. Xxvii-Xxix; 1889, P. Viii; 1890; 1891.
This NBER data series a03003j appears on the NBER website in Chapter 3 at http://www.nber.org/databases/macrohistory/contents/chapter03.html.
NBER Indicator: a03003j
Release: NBER Macrohistory Database
National Bureau of Economic Research, Revenue Per Freight Ton-Mile, Six Railroads for United States [A0303JUSA259NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/A0303JUSA259NNBR/, July 29, 2015.