Source: NBER Series 07023, Total Exports; NBER Series 07028, Total Imports
This NBER data series m07047 appears on the NBER website in Chapter 7 at http://www.nber.org/databases/macrohistory/contents/chapter07.html.
NBER Indicator: m07047
Release: NBER Macrohistory Database
National Bureau of Economic Research, Merchandise Trade Balance: Excess of Total Exports Over General Imports for United States [M07047USM144NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/M07047USM144NNBR/, July 4, 2015.