This Series Has Been Adjusted For Trend As Well As For Seasonal Variation. Source: 1884-1918 Data Are From "Index Of Business Activity In The Pittsburgh District, 1884-1936, " A Leaflet Prepared By The Bureau Of Business Research, University Of Pittsburgh; 1919-1953 Data Are From The Pittsburgh Business Review, June 30, 1943, P. 13; December 1948, P. 3, And Monthly Issues Thereafter.
This NBER data series m12009aa appears on the NBER website in Chapter 12 at http://www.nber.org/databases/macrohistory/contents/chapter12.html.
NBER Indicator: m12009aa
Release: NBER Macrohistory Database
National Bureau of Economic Research, Index of Business Activity for Pittsburgh, PA [M129AAUS38300M511SNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/M129AAUS38300M511SNBR/, July 7, 2015.