Data For 1907-October 1910 And 1932-1963 Exclude Switching And Terminal Companies. During Processing An Extra Decimal Was Added To Original Data, Beginning In January 1913 To Maintain Consistency With Earlier Data. Beginning In 1936 And 1937 Data Include Accruals Resulting From Excise Taxes Levied Under The Social Security Act Of 1935 And The Taxing Act Of 1937; Also Credits Resulting From Refusal Of Changes Previously Made. Beginning In 1962, Only Quarterly Data Are Published By The Icc; The Monthly Figures Presented Were Derived By NBER. Source: Interstate Commerce Commission, Data For 1907-1909: "Bulletin Of Revenues And Expenses Of Steam Roads In The United States", No. 5, P. 13; No. 18, P. 13; No. 31, P. 13. Data For 1910-1921: "Statistics Of Railways", 1921, P. C. Data For 1922-1963: "Operating Revenues And Operating Expenses Of Class I Steam Railways In The United States".
This NBER data series m03038 appears on the NBER website in Chapter 3 at http://www.nber.org/databases/macrohistory/contents/chapter03.html.
NBER Indicator: m03038
Release: NBER Macrohistory Database
National Bureau of Economic Research, Railway Tax Accruals, Class I Railroads for United States [M03038USM133NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/M03038USM133NNBR/, September 3, 2015.