Source: Simon Kuznets, National Product Since 1869 (NBER), 1946, Table I-13, P.50
This NBER data series a10037 appears on the NBER website in Chapter 10 at http://www.nber.org/databases/macrohistory/contents/chapter10.html.
NBER Indicator: a10037
Release: NBER Macrohistory Database
National Bureau of Economic Research, Gross Capital Formation, Total, In Current Prices for United States [A10037USA144NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/A10037USA144NNBR/, August 3, 2015.