Data Represent Cargo In Toll-Paying Ocean Going Commercial Vessels Of 300 Or More Net Tons (Panama Canal Measurement). The Panama Canal Opened August 15, 1914. The Canal Was Closed Between September 18, 1915 And April 15, 1916 Because Of Slides. The Raw Figure For January 1920 (895) Is Confirmed By The Survey Of Current Business. Later Issues Of The Panama Record Give 924, But That Is The Figure For December 1919. Source: The Panama Canal Record, Monthly Since 1937.
This NBER data series m03028 appears on the NBER website in Chapter 3 at http://www.nber.org/databases/macrohistory/contents/chapter03.html.
NBER Indicator: m03028
Release: NBER Macrohistory Database
National Bureau of Economic Research, Panama Canal Traffic, Cargo for United States [M03028USM576NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/M03028USM576NNBR/, July 3, 2015.