Appeared in Industrial and Labor Relations Review, Vol. 46, No. 3, April 1993, pp. 574-78.
Union Membership and Coverage Files from the Current Population Surveys: Note
Barry T. Hirsch and David A. Macpherson*
September 1992
Abstract This note informs readers about the availability of disaggregate annual unionization data compiled from the Current Population Surveys (CPS). Union membership, membership density, and contract coverage density are calculated for employed civilian wage and salary workers from the monthly CPS for January 1983 through December 1991. Workers are classified by demographic and labor market characteristics, industry, occupation, state, metropolitan area, and state-by-industry. The union membership and coverage files described in the note are available from the authors, without charge, in machine-readable form.
*Barry Hirsch is Professor of Economics and David Macpherson is Associate Professor of Economics, both of the Florida State University at Talla hassee. The authors thank an anonymous referee for comments on a previous draft, and Ron Tucker and Greg Weyland of the Bureau of the Census, who answered our many questions about the CPS. The union membership and coverage files described in this paper are provided free of charge, in ASCII format, either by transmission over Internet or on diskette via mail. The authors can be reached by mail at the Department of Economics, Florida State University, Tallahassee, Florida 32306-2045, or at the following Internet addresses:
[email protected] or
[email protected].
In this note we describe union membership and coverage files we have compiled from the Current Population Surveys (CPS) and report how readers can obtain copies of these data. Beginning in January 1983, the CPS, conducted by the Bureau of the Census, adopted new industry and occupation codes and began collecting information each month on union membership and contract coverage. We have compiled annual union membership, membership density, and contract coverage density figures from the January 1983 through December 1991 CPS monthly surveys, disaggregated by industry, occupation, state, metropolitan area, and state-by-industry group. Such information is provided neither by the Bureau of the Census nor the Bureau of Labor Statistics.1 The union membership and coverage files described in this note are available from the authors on request. Moreover, we expect to continue updating the files and to make future updates available. Data from the Current Population Surveys have been the primary basis for estimates of union density for detailed industries, occupations, states, and metropolitan areas. Union density typically has been measured as the percentage of employed wage and salary workers who are union members or are covered by a collective bargaining agreement. Freeman and Medoff (1979) provided union membership density figures for private sector workers based on the combined 1973-75 May CPS. Kokkelenberg and Sockell (1985) calcula ted membership densities among all wage and salary workers as three-year moving averages (along with some annual estimates) for May 1973-75 through May 1979-81. Curme, Hirsch, and Macpherson (1990) utilized the May or May/June CPS tapes for 1983-85, and all monthly CPS surveys for the years 1986-88. They presented both union membership and contract coverage densities, provided area density figures separately for private- and public-sector workers, provided union density estimates for industries and occupations using 1980 Census of Population codes (adopted by the CPS in 1983), and provided data for newly defined metropolitan areas (MSA/CMSA’s) for 1986-88. These three studies have provided a valuable database for industrial and labor relations research.
1
As noted below, the union membership and coverage files expand and update data previously made available by Curme, Hirsch, and Macpherson (1990). The new files were developed following requests from researchers, government agencies, news media, and others. The BLS does not provide disaggregated union data.
Union Membership and Coverage Files: Description The union membership and coverage files summarized in this note provide a substantial extension and update of the study by Curme, Hirsch, and Macpherson (CHM). CHM utilized the monthly CPS surveys for 1986-88. We provide annual estimates from the monthly CPS surveys back to 1983, and forward through 1991. The 1983 estimates are particularly valuable since disaggregated union membership data are not widely available for the early 1980s, a period of particularly important changes (Kokkelenberg and Sockell end their study with 1980, measured by the average of the May samples for 1979-1981). In addition to figures made available by CHM, we include data on union membership as well as membership and contract coverage densities. We also include figures on unionization at a state-by-industry level (22 major industries cross-classified by the 50 states and the District of Columbia) that can be readily matched to alternative industry-by-region units of analysis employed in empirical studies. Our estimates differ from CHM’s and those of previous studies by the exclusion of 14-15-year-olds. Because these new figures include only those workers ages 16 and over, they are exactly comparable to the economywide figures provided by the Bureau of Labor Statistics in Employment and Earnings (January issues), and they follow the standard convention used by the government in defining the labor force, which is restricted to persons age 16 and over.2 Union density estimates are based on calculations from the monthly Current Population Surveys (CPS), household surveys conducted by the Bureau of the Census.3 Households are in the sample for four months, followed by eight months out of the sample, followed by an additional four months in the sample. 2
The BLS publishes data for a few highly aggregated categories based on demographic group, public/private status, and major occupation and industry groups (Employment and Earnings, January issues), but dose not provide more disaggregate figures. The only difference of which we are aware between BLS aggregate figures and our own relate to public/private status. The BLS provides breakdowns with private and public wage and salary workers in nonagricultural employment, but not for workers in agricultural employment. In our figures (economywide and by state and metropolitan area), private and public figures are calculated for all wage and salary workers, including those in agriculture. 3 Technical documentation on the CPS is available in the codebooks that accompany CPS public use tapes. Documentation and public use tapes can be purchased from the Customer Services Branch, Data User Services Division, Bureau of the Census, Washington, D.C. 20233 (301-763-4100), and are also available through the Interuniversity Consortium for Political and Social Research (ICPSR) at the University of Michigan. The annual “microdata files” (or “outgoing rotation group” files) containing monthly union information from January 1983 forward are not public use tapes. They are made available by the Data Services Group at the Bureau of Labor Statistics, accompanied by a record layout of the files (BLS Microdata File, Record Layout).
A supplementary survey containing questions on union membership status is asked of wage and salary workers in the outgoing rotation groups (groups 4 and 8). Our sample of workers includes all employed civilian wage and salary workers, ages 16 and over, in the outgoing rotation groups of the CPS from January 1983 through December 1991. Sample sizes (OBS) by year are provided in Table 1. Membership and contract coverage information is based on responses to two survey questions that remained constant throughout the period. Individuals are counted as union members if they respond yes to the question, “On this job, is ... a member of a labor union or of an employee association similar to a union?” Those who answer no to the union membership question above are then asked, “On this job, is ... covered by a union or employee association contract?” Workers are counted as covered if they are union members or if they are nonunion but covered by a union contract.4 Membership and contract coverage densities, MEM and COV respectively, which measure the percentages of employed wage and salary workers who are union members or are covered by a union contract, respectively, are calculated as follows: (1)
DENj = (Ói äij Wij /Ói Wij ) 100.
DENj represent the percentage of union members or workers covered by a contract in group j, where j is, say, industry, occupation, state, or metropolitan area, and äij is a binary variable equal to 1 if worker i is a union member (or covered); and Wij is the sampling weight assigned by the CPS to worker i, based on the number of similar workers expected to be found in the labor force. Note that self-employed workers and military personnel are not included in the calculations; thus, union densities as calculated here and elsewhere overstate the extent of unionization among all employed workers. Union membership, MEMBERSHIP j , for group j is defined as (2)
MEMBERSHIP j = Ói äij Wij /12,
the sum of the weights over the year for union members in group j, divided by 12 (since 12 monthly surveys are used).
4
Union status is recorded for all workers. The Census Bureau assigns responses for individuals unable to provide answers (approximately 2%), based on characteristics such as industry, occupation, age, race, and gender.
Table 1 provides information on union membership (MEMBERSHIP), membership density (MEM), contract coverage density (COV), and CPS sample sizes (OBS) for employed civilian wage and salary workers, ages 16 and over. Data are for 1983-91 and are classified based on private and public sector status. Union membership declined during this period from 17.7 million in 1983 to 16.6 million in 1991. Private sector membership declined from 12.0 to 9.9 million over the period, whereas public sector membership increased from 5.7 to 6.6 million. By 1991, union membership and contract coverage densities in the private sector were 11.7% and 12.9%, respectively, as compared to 36.9% and 43.3% in the public sector. The purpose of this note is to inform readers of the availability of union membership and coverage files containing data identical to Table 1 for detailed industries, detailed occupations, states, states-byindustries, SMSAs, and MSA/CMSAs. For each classification and year, information for 1983-91 (unless otherwise noted) is available for the following: CPS sample size (OBS), union membership (MEMBERSHIP), membership density (MEM), and contract coverage density (COV). The number of workers covered by contracts can be approximated by MEMBERSHIP · (COV/MEM), and the number of the employed wage and salary workers can be approximated by (MEMBERSHIP/MEM) · 100. The files described in Table 2 are provided in machine-readable form, on request, without charge.5 Conclusion We have used CPS surveys from January 1983 through December 1991 to compile detailed union membership, membership density, and contract coverage density figures for industries, occupations, states, metropolitan areas, and state-by-industries, as well as for workers based on demographic and labor market characteristics.
5
Alternative files containing employment figures can be provided on request.
References Michael A. Curme, Barry T. Hirsch, and David A. Macpherson. 1990. “Union Membership and Contract Coverage in the United States, 1983-1988.” Industrial and Labor Relations Review, Vol. 44, No. 1 (October), pp. 5-33. Freeman, Richard B. and James L. Medoff. 1979. “New Estimates of Private Sector Unionism in the United States.” Industrial and Labor Relations Review, Vol. 32, No. 2 (January), pp. 143-74. Kokkelenberg, Edward C. and Donna R. Sockell. 1985. “Union Membership in the United States, 19731981.” Industrial and Labor Relations Review, Vol. 38, No. 4 (July), pp. 497-543. U.S. Bureau of Labor Statistics. Annually. Employment and Earnings. Washington, D.C.: GPO, January. U.S. Bureau of Labor Statistics. Annually, 1983-1991. BLS Microdata File, Record Layout, Washington, D.C.: Data Services Group.
Table 1. Union Membership, Membership Density, and Contract Coverage Density, 1983-1991. Year
Sample
OBS
MEMBERSHIP
MEM
COV
1991:
All workers Private Public All workers Private Public All workers Private Public All workers Private Public All workers Private Public All workers Private Public All workers Private Public All workers Private Public All workers Private Public
179,560 147,112 32,448 185,030 152,197 32,833 176,411 145,372 31,039 173,118 142,409 30,709 180,434 148,698 31,736 179,147 147,678 31,469 180,232 148,185 32,047 177,248 145,104 32,144 173,932 141,311 32,621
16,568,443 9,936,480 6,631,963 16,739,812 10,254,800 6,485,012 16,960,452 10,536,230 6,424,222 17,001,665 10,702,439 6,299,226 16,913,064 10,857,316 6,055,748 16,975,180 11,084,659 5,890,521 16,996,101 11,252,959 5,743,142 17,339,763 11,684,046 5,655,717 17,717,379 11,980,183 5,737,196
16.12 11.72 36.86 16.11 11.91 36.47 16.39 12.25 36.73 16.77 12.71 36.64 17.03 13.17 35.91 17.52 13.77 35.94 17.98 14.34 35.74 18.81 15.30 35.72 20.07 16.49 36.70
18.23 12.90 43.33 18.34 13.20 43.25 18.55 13.47 43.53 18.97 13.96 43.54 19.18 14.42 42.49 19.89 15.16 43.16 20.48 15.85 43.06 21.62 17.01 43.87 23.26 18.47 45.49
1990:
1989:
1988:
1987:
1986:
1985:
1984:
1983:
Source: The Current Population Survey Microdata Files,January 1983 through December 1991.
The sample consists of employed civilian wage and salary workers, ages 16 and above. OBS is the CPS sample size, MEMBERSHIP is estimated union membership of the group (the sum of the union member sample weights/12), MEM is the union membership density, and COV is the contract coverage density. MEMBERSHIP, MEM, and COV are further defined in the text.
Table 2. Union Membership and Coverage Files, 1983-1991. Designation SUMMARY.TAB IND3.A_1 OCCUP3..A_2 STATE.A_3 SMSA.A_4
MSA.A_5
STATEIND.A_6
Description Membership and Coverage, 1983-1991. Three summary tables with economy -wide data by class of worker, demographic group, major industry, and major occupation. Membership and Coverage by Detailed Industry, 1983-1991. Data for 231 three-digit Census of Population industries. Membership and Coverage by Detailed Occupation, 1983-1991. Data for 503 three-digit Census of Population occupations. Membership and Coverage by State for All Workers, Private Sector Workers, and Public Sector Workers, 1983-1991. Data for 50 states and the District of Columbia. Membership and Coverage by SMSA for All Workers, Private Sector Workers, and Public Sector Workers, 1983-1984 and 1/85-9/85. Data for 44 Standard Metropolitan Statistical Areas. Membership and Coverage by MSA/CMSA for All Workers, Private Sector Workers, and Public Sector Workers, 10/85-12/85 and 1986-1991. Data for 202 Metropolitan Statistical Areas and Consolidated Metropolitan Statistical Areas. Membership and Coverage by Major Industry by State, 1983-1991. Data for 1,122 stateby-industry categories (22 major industries times 50 states plus D.C.).
