Ever hear complaints about Big Banks, Big Oil and Big Pharma? I'll bet you have. But there's another "Big" that you rarely hear about -- Big Unions.

And I'm not talking about private company unions -- like auto and steel workers. Only 6.7% of workers belong to private sector unions. No, I'm talking about Public Employee Unions.

They're very big. And very powerful. Far bigger and more powerful than most people know. In fact, the impact they have on how state and local governments operate makes Big Banks, Big Oil and Big Pharma look small by comparison. But before I explain why, I should explain who the Public Employee Unions are. They are the unions that represent policeman, fireman, sanitation workers, teachers, and the vast army of others -- the bureaucrats -- who administer city, state and federal governments.

The public service unions negotiate on behalf of these workers for their wages, benefits, and working conditions. And who is the on other side of the table? Our elected representatives, the people in charge of spending the money we pay to government in taxes.

Think about this for a moment and you will immediately realize that the goal of the public employee unions is to negotiate with union-friendly politicians.

And the way to get friendly with a politician is to help him get elected. Which is exactly what the unions do. First, they have a lot of money. In many states, working for the government is a closed shop: that is, to work for the government you have to pay dues to the union. This guarantees these unions a large membership and a large pot of cash. Spreading this money around, especially in local elections, goes a long way.

Second, unions provide union-friendly candidates, at no charge, with seasoned political activists to help run campaigns. These activists marshall other union members to put up campaign signs, work the phones, and gather up loyal voters on election day.

This is a proven strategy. And candidates, especially in the big cities where there are a lot of public employees, know it. Courting union support is critical to victory.

"We will fight for a fair contract!" New Jersey gubernatorial candidate, Jon Corzine, said to a rally of 10,000 public workers in 2006. But fight who for a fair contract? The person the unions would be "fighting" if Corzine were to win the election (he did) is . . . Corzine!

The Speaker of the New York State Assembly once told a United Federation of Teachers rally "I and my colleagues in the Assembly majority will be your best friends . . . in Albany." Exactly right.

In California in 2010 an official of the Service Employees International Union, known by its initials, the SEIU, told elected officials: "We helped to get you into office, and we got a good memory . . . Come November, if you don't back our program, we'll get you out office."

Again, exactly right. As Dan Walters of The Sacramento Bee wrote, "public employee unions wield immense, even hegemonic influence over the Democratic majorities in the state legislature."

What is the consequence of all this power? The most obvious consequence is that cities and states overpay their workers -- by a lot.

Trash collection in Dallas, Texas, a state whose government workers are not unionized, costs $74 per ton. Trash collection in Chicago, whose government workers are unionized, costs $231 per ton. These kinds of inefficiencies exist everywhere public unions dominate.

But this is just the tip of the iceberg. The iceberg is the pension arrangements that provide public employees with retirement benefits that vastly exceed the retirement benefits in the private sector. Four cities in California -- Vallejo, Stockton, Mammoth Lakes and San Bernardino -- have declared bankruptcy largely because of the burden of paying public employee pensions. The same is true of Detroit, the nation's largest bankruptcy ever.

And it's only getting worse. By 2030 the number of retired public workers will equal the number of working public workers.

You can read more about this in my book Government against Itself, but suffice it to say this is not a pretty picture. All this spending on public service unions crowds out tax money for things we need -- such as better roads, services and schools.

Finally, some courts and politicians have summoned the courage to make much needed reforms. But it's never easy, as we saw in Wisconson in when thousands of union protesters overran the state capitol for weeks.

But reform is coming. It must. If it doesn't, cities like Detroit will be the rule, not the exception.

So, the next time someone complains about Big Banks, Big Oil or Big Pharma, ask if they are equally concerned about Big Unions.

They should be.

I'm Daniel DiSalvo, assistant professor of Political Science at the City College of New York.