Daily Averages Are Used Through January 1935. Thereafter, Midmonth Figures Were Computed Based On End Of Month Data. New York Central Figures Are Not Available, 02-12/1920; Missouri-Pacific Figures Are Not Available, 02-03/1920; Fort Smith And Western Are Not Available, 03/1920. Switching And Terminal Companies Are Excluded Through December 1936. They Are Included Thereafter Beginning In February 1937. The January 1937 Figure Is The Average Of The 12/1936 And 02/1937 Figures. Series 01264 Is Computed By NBER By Subtracting Series 01251 (Serviceable Locomotives Assigned To Freight Service) From Series 01250 (Total Locomotives Assigned To Freight Service). The Notes And Sources Given Above Are From Those Two Series. Source: 1920-1934 Data Are From Interstate Commerce Commission, Freight And Passenger Service Operating Statistics Of Class I Steam Railways In The United States; 1935-1942 Data Are From Icc, Motive Power And Car Equipment Of Class I Steam Railways In The United States.
This NBER data series m01264b appears on the NBER website in Chapter 1 at http://www.nber.org/databases/macrohistory/contents/chapter01.html.
NBER Indicator: m01264b
Release: NBER Macrohistory Database
National Bureau of Economic Research, Unserviceable Locomotives Assigned To Freight Service, Class I Railroads for United States [M0164BUSM481SNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/M0164BUSM481SNBR/, August 27, 2015.