Source: Computed By NBER By Subtracting Series 01253 (Total Freight Cars On Line, Class I R.R.) From Series 01254 (Serviceable Freight Cars On Line, Class I R.R.).
This NBER data series m01265 appears on the NBER website in Chapter 1 at http://www.nber.org/databases/macrohistory/contents/chapter01.html.
NBER Indicator: m01265
Release: NBER Macrohistory Database
National Bureau of Economic Research, Unserviceable Freight Cars On Line for United States [M01265USM559SNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/M01265USM559SNBR/, November 28, 2015.