Concerning 1930 Data: The Federal Reserve Board Issued A Mimeographed Sheet Which Gave Percentage Changes In Wholesale Trade In Dry Goods (The Month Of One Year Over The Month Of The Previous Year). These Percentages Were Used To Carry The Index From December 1929 To December 1930. Source: Federal Reserve Board, Bulletin Of December 1927, Pp. 826-827, And Following Issues
This NBER data series m06015 appears on the NBER website in Chapter 6 at http://www.nber.org/databases/macrohistory/contents/chapter06.html.
NBER Indicator: m06015
Release: NBER Macrohistory Database
National Bureau of Economic Research, Index of Wholesale Trade Sales, Dry Goods for United States [M06015USM331SNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/M06015USM331SNBR/, October 13, 2015.