Series Is Presented Here As Three Variables--(1)--Seasonally Adjusted Data, 1921-1939 (2)--Seasonally Adjusted Data, 1939-1946 (3)--Seasonally Adjusted Data, 1946-1968. Data Represent One Quarter Span At Annual Rate, Defined As: The Difference Between The Value Of The Month M And The Value Of The Month M+3 Is Divided By The Month M And Multiplied By 4. Source: Office Of Business Economics, Barger And Klein.
This NBER data series q08362a appears on the NBER website in Chapter 8 at http://www.nber.org/databases/macrohistory/contents/chapter08.html.
NBER Indicator: q08362a
Release: NBER Macrohistory Database
National Bureau of Economic Research, Rate of Change In Current Prices, Gross National Product for United States [Q0862AUSQ156SNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/Q0862AUSQ156SNBR/, July 1, 2015.