Source: Business Cycle Developments, March 1964, For 1949-1962 Data; August, 1966 And Following Months For 1963 And Later Data.
This NBER data series m08310 appears on the NBER website in Chapter 8 at http://www.nber.org/databases/macrohistory/contents/chapter08.html.
NBER Indicator: m08310
Release: NBER Macrohistory Database
National Bureau of Economic Research, Average Weekly Insured Unemployment Rate, State Programs, Excluding Puerto Rico for United States [M08310USM156SNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/M08310USM156SNBR, February 6, 2016.