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For questions about the data:  contact Rob Valletta (; 415-974-3345)

Additional details are provided in:

R.G. Valletta and R.B. Freeman, "The NBER Public Sector Collective Bargaining Law Data Set." Appendix B in Richard B. Freeman and Casey Ichniowski, editors, When Public Employees Unionize   Chicago: NBER and University of Chicago Press, 1988.

Please cite this appendix in any written work that uses these data.  It is an important source of documentation; for example, for details about the compilation and structure of the data set, see especially footnotes 1-3 in the appendix.

The complete data set is contained in the Stata data file publaw.dta. In addition, the file publaw.raw contains the data in comma-separated value format, suitable for reading into a spreadsheet or other data program.  For individuals who use the latter, the accompanying Stata program, defines the variables (using labels) and indicates the ordering in the raw data file. The Stata command 'copy "" publaw.dta' will copy the .dta file to your current directory.


The data set consists of observations for 5 state and local government employee groups in 50 states over about 30 years from 1955-1985 for a total of 7570 observations. The first four variables are identifiers for the state, the employee group, the month, and the year. The month variable is coded “0” if no change in the law appeared in that year. In general, non-zero values of the month variable indicate the month (1 through 12) that a change in the law occurred. The value “13” indicates that the month of the change is unknown. Please note that for years in which a change in the law occurs, the new provisions appear in the observation for the next year. Also, for the final yearly observations for each group-state (which will be either 1985 or 1984), the value of the month variable indicates the latest date through which the data were verified, which varies from state to state.


For each group-state-year, the status of state bargaining law is summarized by 14 numerical variables.  These variables represent the features of the law deemed most relevant for union activity. In some states, judicial decisions also have played a role in the evolution of the legal status of collective bargaining by public employees; this is beyond the scope of the data set. Tables 1A-E in the Valletta and Freeman appendix (pages 400-403) indicate how the legal variables are coded. The rest of the appendix presents simple descriptive statistics.

The additional documents, publaw_vars.htm and publaw_notes.htm, respectively, list the numerical coding scheme for the identifying variables (employee group and state), and the idiosyncratic features of the data.

Kim Rueben extended the variables concerned with collective bargaining rights, rights, and right to work laws, rgtowork, through 1996. union96.doc has the supplemental documentation and the data is in Stata or Excel format. and contain SAS code used to look at and update analyze the data respectively.

Last Update: February 25, 2010 

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