Series (Serviceable Freight Cars) Includes Switching And Terminal Companies From February 1937 On. Series (Revenue Ton-Milies) Excludes These Trhoughout. Data For This Series From 1920-January 1935 Are Based On Daily Averages; Data From February 1935-1943 Are Based On First Of The Month Data, The Published End-Of-Month Figures Being Placed Forward One Month, Centered By A Moving Average On The Second Month. Source: Computed By NBER By Dividing Series (Revenue Ton-Miles) By Series (Serviceable Freight Cars); Both Series Are Based On Interstate Commerce Commission Sources.
This NBER data series m03056 appears on the NBER website in Chapter 3 at http://www.nber.org/databases/macrohistory/contents/chapter03.html.
NBER Indicator: m03056
Release: NBER Macrohistory Database
National Bureau of Economic Research, Revenue Ton-Miles Per Serviceable Freight Car, Class I Railroads for United States [M03056USM594NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/M03056USM594NNBR/, October 13, 2015.