Series Is Presented Here As Two Variables--(1)--Original Data, 1877-1941 (2)--Original Data, 1941-1964. Data Are For Daily Averages Computed By Dividing Monthly Figures By The Number Of Days Within The Month. Source: Data For 1941-1944: Iron Age, January 7, 1954 (Annual Review And Forecast Issue. Data For 1945-1964: American Iron And Steel Institute, Annual Statistical Report For 1952-1963; And Aisi, Form 7: Blast Furnace And Steel Production (Monthly).
This NBER data series m01130b appears on the NBER website in Chapter 1 at http://www.nber.org/databases/macrohistory/contents/chapter01.html.
NBER Indicator: m01130b
Release: NBER Macrohistory Database
National Bureau of Economic Research, Pig Iron Production for United States [M0130BUSM583NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/M0130BUSM583NNBR/, July 29, 2015.