Source: Interstate Commerce Commission, Bureau Of Statistics, Freight Commodity Quarterly
This NBER data series q03062 appears on the NBER website in Chapter 3 at http://www.nber.org/databases/macrohistory/contents/chapter03.html.
NBER Indicator: q03062
Release: NBER Macrohistory Database
National Bureau of Economic Research, Revenue Tons Originated, Class I Steam Railways, Total for United States [Q03062USQ455NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/Q03062USQ455NNBR/, October 9, 2015.