Series Is Presented Here As Two Variables--(1)--Original Data, 1948-1961 (2)--Original Data, 1959-1968. Source: Data For 1948-1960: U.S. Bureau Of The Census, Business Cycle Developments, July 1964. Data For 1961: Secured By Phone Direct From The First National City Bank On December 1, 1964. This NBER data series m13047a appears on the NBER website in Chapter 13 at http://www.nber.org/databases/macrohistory/contents/chapter13.html. NBER Indicator: m13047a