Release: NBER Macrohistory Database
Source: Interstate Commerce Commission, Data For 1921-1933: "Passenger Train Performance". Data For 1934: "Freight And Passenger Service Operating Statistics", Statement 210. Data For 1935-1943: Direct From Icc Files.
This NBER data series m03063 appears on the NBER website in Chapter 3 at http://www.nber.org/databases/macrohistory/contents/chapter03.html.
NBER Indicator: m03063
National Bureau of Economic Research, Total Passenger Locomotive Miles for United States [M03063USM227NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/M03063USM227NNBR, July 24, 2016.