Data Represent Commercial Bars, .999 Fine, In Troy Ounces, Produced By The Refineries From Both Domestic And Foreign Ores. Source: Data For 1921-1936, 1943-1944: Directly From The American Bureau Of Metal Statistics. Data For 1937-1942: Metal Statistics.
This NBER data series m01143a appears on the NBER website in Chapter 1 at http://www.nber.org/databases/macrohistory/contents/chapter01.html.
NBER Indicator: m01143a
Release: NBER Macrohistory Database
National Bureau of Economic Research, Silver Production for United States [M0143AUSM409NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/M0143AUSM409NNBR, May 1, 2016.