The Stock Exchange Was Closed August-November, 1914. There Are No Data For August And September And Only Unofficial Data For October And November. The December, 1919 Entry Was Misprinted As 224.6 In The June, 1923 Supplement To The Review Of Economic Statistics, P.169. Here It Is Given As 229.6. The Total For 1923 Is Of Data For 5 Months. Source: Frickey, Review Of Economic Statistics, August, 1921, Pp.275-277; June, 1923 Supplement (Statistical Record) P.169
This NBER data series m11007 appears on the NBER website in Chapter 11 at http://www.nber.org/databases/macrohistory/contents/chapter11.html.
NBER Indicator: m11007
Release: NBER Macrohistory Database
National Bureau of Economic Research, Index of Common Stock Prices, New York Stock Exchange for United States [M11007USM322NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/M11007USM322NNBR/, October 13, 2015.