Series Is Presented Here As Two Variables--(1)--Original Data, 1895-1928 (2)--Original Data, 1920-1941. Data For 1895-1903 Are Weekly Averages Derived By NBER By Dividing Monthly Figures By The Number Of Weeks Ending On Saturdays Having A Majority Of Days In A Given Month. Data Are For The Joplin District, Also Known As The Tri-State District. This Area Includes Parts Of Missouri, Kansas And Oklahoma And Produces About Two-Thirds Of The Ore Mined In The United States. Source: Data For 1895-1903: Computed By NBER From Data In Engineering And Mining Journal. Data For 1904-1928: Official Daily Market Reports Of New York Metal Exchange.
This NBER data series m01141a appears on the NBER website in Chapter 1 at http://www.nber.org/databases/macrohistory/contents/chapter01.html.
NBER Indicator: m01141a
Release: NBER Macrohistory Database
National Bureau of Economic Research, Zinc Ore Shipments, Joplin District for Joplin, MO [M0141AUS27900M526NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/M0141AUS27900M526NNBR/, October 3, 2015.