Source: Minneapolis Chamber Of Commerce, Annual Reports.
This NBER data series m01059 appears on the NBER website in Chapter 1 at http://www.nber.org/databases/macrohistory/contents/chapter01.html.
NBER Indicator: m01059
Release: NBER Macrohistory Database
National Bureau of Economic Research, Flour Shipments for Minneapolis, MN [M01059US33460M535NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/M01059US33460M535NNBR, April 30, 2016.