The Basic Sources Used For Compilation Of This Series Were Various Annual Issues Of "Merchant Marine Statistics" (Originally Prepared By The Commerce Department And Now Issued By The Bureau Of Customs), Supplemented By Records Of The Bureau Of Customs. This Series Covers Documented Merchant Vessels Of Five Gross Tons Or More That Were Granted Registers, Enrollments And Licenses , Or Licenses As "Vessels Of The United States." Documentation, Which Implies Ownership By United States Citizens, Confers Certain Benefits And Privileges, Such As That Of Engaging In Coasting Trade. These Data Are Reported In "Gross Tonnage," Which Refers To Space Capacity Rather Than Weight. Currently One Ton Is Considered Equivalent To 100 Cubic Feet; Before 1865, One Ton Equaled 95 Cubic Feet. For 1797-1834 Data, Years Ended December 31; 1835-1842, September 30; 1843-1940, June 30; And 1941-1962, January 1. Figures For 1835 And 1843 Cover Only Nine Months. Figures For 1938-62 Are Not Comparable With Those For Earlier Years As They Represent Only Those Vessels Still In Existence As Part Of The Merchant Fleet At The End Of The Twelve-Month Period In Which They Were Built. Therefore, They Exclude Those Vessels Which Were Lost, Sold To The U.S. Government, Sold To Aliens, Or Removed From The Merchant Fleet For Any Other Reason, Before The End Of The Period. Source: 1797-1957:"Historical Statistics Of The United States, Colonial Times To 1957", Bureau Of The Census, Series Q179. 1958-1962: "Historical Statistics Of The United States, Continuation To 1962 And Revisions, " Bureau Of The Census.
This NBER data series a02244 appears on the NBER website in Chapter 2 at http://www.nber.org/databases/macrohistory/contents/chapter02.html.
NBER Indicator: a02244
Release: NBER Macrohistory Database
National Bureau of Economic Research, Merchant Vessels Built and Documented, Tonnage for United States [A02244USA309NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/A02244USA309NNBR/, July 5, 2015.