Data Compiled By NBER By Adding Items;"First Track," "Other Main Track," And "Yard Track And Sidings." Switching And Terminal Companies Included Through 1907 But Excluded Thereafter. Data For The First Two Segments Are For June 30, Midpoints Of Calendar Years, 1890-1916; Data For The Third Segment, For December 31, 1916-42, Midpoints Of Fiscal Years Ending June 30, 1917-43. The Third Segment Can Be Adjusted To Midpoints Of Calendar Years By Averaging Preceding And Following December Figures, I.E., June 1916 = (December 1915 + December 1916) /2. Source: Interstate Commerce Commission, "Statistics Of Railways In The United States", 1926, P. Xcviii; 1934, P. S-106; 1942, P. 152.
This NBER data series a02133 appears on the NBER website in Chapter 2 at http://www.nber.org/databases/macrohistory/contents/chapter02.html.
NBER Indicator: a02133
Release: NBER Macrohistory Database
National Bureau of Economic Research, Total Track Mileage of Railroads for United States [A02133USA581NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/A02133USA581NNBR/, November 24, 2015.