Last winter, columnist Nicholas Kristof wrote about changing his mind on the subject of labor unions, deciding that the negative consequences of their decline in the United States outweighs horror stories about corruption and overpaid workers. Kristof cited studies suggesting that at least one-fifth and as much as one-third of the increase in economic inequality among men in this country can be attributed to unions' shrinking influence since the mid-20th century.

Others have observed the link between declining union membership and income inequality; a white paper published last year by the International Monetary Fund examining 20 developed economies found that the decline in unionization is related to the rise of top income shares and less redistribution, with a negative correlation between union presence and the incomes of top earners.

Labor unions’ impact on income is not simply the result of fewer workers being paid under union contracts; even in their 1950s heyday only about a third of American workers were union members. Rather, as political scientists Joseph Hacker and Paul Pierson wrote in their 2010 paper (and later book) Winner-Take-All-Politics, it is “the political role of organized labor on issues of economic and social policy that matters most in the political economy.” Unions have long been the strongest, most organized political actor supporting workers' rights on the national stage, and their decline has left America without a special interest capable of countering pro-business groups such as ALEC and the U.S. Chamber of Commerce.

There are a few generally cited explanations for the decline of unions in the United States: shrinking employment in manufacturing, mining, and other heavy industries; legislative changes such as the 1947 Taft-Hartley Act and anti-union “right-to-work” laws; the government’s assumption of responsibility for worker protections previously secured by collective bargaining, (such as through OSHA, the ADA, and mandated health coverage); and decreased public awareness and respect for the Progressive labor movement and its heroes.

I would venture, however, that a cultural thread helps tie these different causes together. As industrial employment declines and the country shifts towards a service economy (more below), there has been no awakening of labor solidarity among bottom-rung service employees. (Note here the term “service employees” goes beyond services like restaurants and retail to include business services like consulting, insurance, accounting, engineering, and the like.) I think you can put some of the blame from this failure on something I'll refer to as Carhartts and Uniforms.

Basically, as the shape of the American economy has moved over time, our conception of the term “labor” hasn't kept pace, and a vast number of workers fail to realize that they are, in fact, laborers. Millions of workers who are in the same basic position as laborers in the 1950 (but in the context of the 2016 economy), even those who's politics match their Progressive forebears, nonetheless fail to think of themselves as members of the laboring class and feel no urge to collectivize.

Take a look at the ten largest unions listed in the Labor Department's Directory of Labor Unions in the United States, 1953, when union employment was near its peak: United Auto Workers, United Steelworkers, Teamsters, Carpenters & Joiners of America, International Association of Machinists, Mine Workers of America, International Brotherhood of Electrical Workers, International Union of Hotel & Restaurant Workers, Amalgamated Clothing Workers, and International Ladies Garment Workers’ Union. For the most part, these unions represented workers you would imagine clocking in wearing either durable work clothes (e.g., Carhartts) or some kind of uniform. Carhartt’s and Uniforms. This holds true quite a ways down the list, with only a handful of exceptions such as the American Federation of Musicians and the Communications Workers of America.

Not much has changed in terms of which private industries are unionized. Today, the list of largest private-sector unions continues to be dominated by Carhartts and Uniforms professions, including stalwarts like the United Steelworkers and the Teamsters and relative newcomers like the Service Employees International Union and the United Food and Commercial Workers.

Yet while many of the same unions top the list in 1953 and 2015, these professions have shrunk vastly as a share of total employment. In 1953, United Steelworkers was the second-largest private union with 1,100,000 members, about 2.5% of the total private-sector workforce. Today, United Steelworkers is still the fourth-largest private union, but has only 860,000 members – about 0.7% of the total private-sector workforce. The fact that this union has remained one of the country's largest, while dropping both in total membership and share of the workforce, reflects both the decline of membership within the industry as well as the decline of manufacturing as a share of total employment.

I don’t claim this to be an original insight – it’s well documented that agriculture and manufacturing long ago ceded their top spots to financial and professional services as the largest employment sectors in the United States, a shift “from factories to cubicles.” It’s also commonly understood that overall union membership has decreased alongside a decrease in traditionally union sectors, chiefly manufacturing, as a share of the U.S. employment. But it is interesting that the labor movement has been stuck with blue-collar industries without gaining more footholds in growing employment sectors.

In 2016, your cubicle job at the lower tier of a business services company occupies the same position in the U.S. economy that a steel press operator did in 1962 – the bottom rung of a major market sector that is largely funneling profits to people above you. As a 2009 white paper in the International Journal of Business and Management puts it, white-collar work has become increasingly "commoditized" as technologies develop to help automate administrative and intellectual tasks, IT systems allow increased offshoring and outsourcing, and white-collar employees shift in ownership’s eyes from long-term partners to capital inputs. Employees are working longer hours (where they aren't limited to part time to reduce benefits), for stagnating or lower effective pay, with declining bargaining power and job security, in organizations that are increasingly restrictive. Though you might be wearing a dress shirt and working with MS Office, you are just as much “labor” as a construction worker or bus driver – even if your job carries the trappings of management.

Over at lefty magazine CounterPunch, playwright and former union negotiator David Macary gets at the idea. Channelling John Steinbeck, Macary argues that working people adopt a “sense of faux-independence . . . . Workers prefer to think of themselves as incipient, yet-to-be-realized entrepreneurs rather than proletarian toilers.” According to Macary, “[w]ith everyone’s sights set on upward mobility, fewer people are comfortable publicly identifying themselves as blue-collar, because doing so cuts them off from the prestige that comes from lucrative jobs/careers.” I wouldn’t pin the blame so squarely on the material aspirations of today’s workers, though – I think Americans have loved the idea of personal success for a very long time, and God bless us for it - but I agree with the notion that workers fail to properly conceive of their own status in the economy.

Thus, while people remain generally supportive of unions – public approval has declined from its high-water mark in the 1950s but still remains well above 50% – there seems to be little urgency by white-collar workers to actually contemplate joining one. Unions are for Carhartts and Uniforms jobs, not for me.

Writer Edward McClelland puts it well (if a bit melodramatically) at Salon. “There’s a popular discounting company in Chicago called Groupon,” he writes, “where the account executives — who are all expected to have bachelors’ degrees — earn $37,800 a year. Adjusted for modern dollars, that’s about [the starting wage of a steelworker in 1965], without overtime. Because they’re educated and sit safely at desks, they don’t think of themselves as blue-collar mopes who need to strike for higher pay and better working conditions.” But they are.

It's a bit mysterious why the progressive anger that is currently fueling American youth and progressives – see Sanders, Bernie – seems to mostly be triggering anger at the top rather than solidarity among the bottom. Senator Sanders’ campaign page on income inequality, for example, includes 13 policy goals, almost all of which focus on mandated benefits, direct services by the federal government, or taxation of the wealthy. Only one proposal, the twelfth, addresses labor unions by supporting the Employee Free Choice Act, which attempts to reduce employers’ ability to frustrate unionization in the time between the decision to unionize and the election of union representatives. (Sanders re-introduced this legislation in the Senate last October, rechristened as the “Workplace Democracy Act.”) Hillary Clinton’s “labor” page is similar, likewise referencing only the Employee Free Choice Act and otherwise discussing government services and statutory labor protections. The platform drafted by the Democratic National Committee in 2012 lacks any specific proposals whatsoever.

If the left wish to reverse decades of increasing income inequality, it must find a way to motivate white-collar progressives to actively support some form of labor movement; white-collar workers will need to be convinced that being pro-union is more than just giving solidarity to exploited blue-collar workers, it is the means by which Americans can have a strong voice in national politics lobbying concretely for employee rights. I doubt that America’s market culture could fully tolerate Europe's industry-wide collective bargaining systems, but perhaps the American left can take some inspiration from a framework in which even non-unionized workers benefit from the advocacy of workers' representatives.

It is unlikely America will ever see the level of union membership that it did after World War II. However, in modern America labor unions have played a crucial role in balancing lobbying efforts by well-funded pro-business organizations, and it is to the country’s detriment that organized labor has declined as a political force. Until white collar workers begin viewing the labor union as something that can benefit them, and not just be for the Carhartts and Uniforms set, the country will only continue down a path towards inequality.