[This text was originally published in AREA Chicago #10 in October 2010]
Union membership ensures higher wages  and many benefits that most non-union workers do not have – a collectively bargained contract, health insurance, pensions, progressive discipline , and the collective power of being a member of a large organization. The collective power in union membership allows workers to fight for higher wages, sick days, and numerous other things to improve their quality of life. However, the power of union membership is not just in the contract. Union members fight for change in policies on the city, state and national level.
Nationally, there are 15.3 million union members in the United States.  This figure represents 12.3% of all workers in this country. 
In 2009, 951,000 people or 17.5% of workers in Illinois belonged to a Union.  While specific statistics for the metro-area are unavailable,  it is safe to assume that the majority of union members in Illinois live in the Chicagoland area. There are over 300 unions representing thousands and thousands of people in the Chicagoland area. Union members accounted for 17.5 percent of wage and salary workers in Illinois in 2009 (versus 21% at its highest in 1993). 
The Political Power
The influence of unions on politics in this country is undeniable (and the influence locally may be stronger than on the national scale). Many union members voluntary contribute to a political fund (Political Action Committee or PAC) sponsored by their union. The union then spends this money contributing to political campaigns in the hopes of gaining better policies for working people.
The majority of political contributions made by unions benefit the Democratic Party.  In Illinois, the National Education Association and the American Federation of Teachers spent $32.72 per teacher for a total of $4,468,363 in Political donations.  Another union, The Service Employees International Union donated $1.7 million to Governor Pat Quinn’s campaign, as reported by The New York Times on February 2, 2010. 
However, when you compare the total contributions of union PACS to business contributions for this upcoming election cycle the disparity between the two is immense. Union PAC contributions only comprise 4% of contributions for the 2010 election cycle.  So while the political power of organized labor is more influential than any other progressive organizational formation, it pales in influence to the private sector business owners and executives.
We should all care about unions. Union members are part of organizations with an access to resources – millions of people and millions of dollars. More importantly, union members can create great social change in our country. In a time where the left is as dis-jointed as ever, unions offer us the best chance to create a world where working people can fight for improvements in their own lives and change for all working families.
Understanding the complexity of all the types of unions is important to understanding power in Chicago. This guide breaks down the types of unions into five categories of workers: Public, Trades, Service, Health, and Entertainment. There is overlap in these categories, and with the expansion of some unions organizing workers not traditionally in their jurisdiction (i.e. Steelworkers organizing graduate students) is a bit messy.
The goal of this guide is to help you understand the breadth of organized union workers and the different unions within each category. When possible, I have included when the charter date of the union, the type of worker the union represents, and how many members the union represents.  In addition, I have included guides to contingent worker organizations; councils that unions organize within; and allies to labor.
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This link will take you to an online text document which contains the directory of Unions in Chicago. The directory will be updated occasionally so please keep in touch with your ideas or let me know if you would like to collaborate.
 Union members make 28% more than non-union members. https://aflcio.org/
 U.S. Department of Labor, Bureau of Labor Statistics, “Union Members in 2009,” January 22, 2010. 15.3 million people are union members, with another 1.6 million people work on a job that is covered by a Union contract but workers do not report affiliation with a union.
 U.S. Department of Labor, Bureau of Labor Statistics, “Union Members in 2009,” January 22, 2010. https://www.bls.gov/news.release/pdf/union2.pdf
 A call to the Illinois Department of Labor provided no results – only confirming the number in the State, and that the majority of union members in the state do live in the Chicagoland area.
 Political Fruit of Labor in Capital Eye Opener: September 6, ByDave Levinthal on September 6, 2010 11:20 AM
 Numbers based on contributions in 2007. For more information, please see “The Long Reach of Teachers Unions” by Mike Antonucci, published in the Fall 2010 Issue of EducationNext.
 Chicago News Cooperative, After a String of Political Victories, a Union Has Clout to Spare By dan Mihalopoulos – Published: February 26, 2010.
 Center for Responsive Politics – Business-Labor-Ideology Split in PAC & Individual Donations to Candidates and Parties
 All of this information has been pulled from the website of the union. Many locals do not have a website, or do not include such data on their website. In reviewing all of these websites, it is clear that the audience for some of these websites is the union member – not the general public. As such, some data is not available online. Further research would be useful to get more information from specific locals.