Everyone knows that teacher unions matter in education politics and policies, a reality that is never more evident than at election time. In recent weeks, for example, state affiliates have been pushing for higher taxes on businesses to boost education spending in Nevada, successfully suing to limit the governor’s authority over education in Wisconsin, and working to sink an initiative to allow charter schools in Washington State. Of course, those instances are but the tip of a very large iceberg. Across the land, unions are doing their utmost to prevent all sorts of changes to education that they deem antithetical to their interests.

The role of teacher unions in education politics and policy is deeply polarizing. Critics (often including ourselves) typically assert that these organizations are the prime obstacles to needed reforms in K–12 schooling, while defenders (typically, also, supporters of the education status quo) insist that they are bulwarks of professionalism and safeguards against caprice and risky innovation.

Yet these arguments have rested on little but anecdote, opinion, and personal observation. There’s been scant real information on how much teacher unions matter, how exactly they seek to wield influence, and whether they wield more of it in some places than others.

There’s plenty of conventional wisdom, to be sure, mostly along the lines of, “unions are most powerful where every teacher must belong to them and every district must bargain with them and least consequential in ‘right-to-work’ states.”

But is that really true? Even if it is, does it oversimplify a more complex and nuanced situation?

In a major study we released this week together with Education Reform Now, How Strong Are U.S. Teacher Unions: A State-By-State Comparison, we dug deep, churning vast amounts of data to parse the differences in political strength across state-level unions in the fifty states plus the District of Columbia.

Let us acknowledge that it’s not a perfect analysis. Let us admit that its conclusions are more nuanced, even equivocal, than we at Fordham are accustomed to. And let us also recognize that, even as we were gathering and analyzing all that data, multiple factors—economic woes, party shifts, court decisions, changing policy agendas, the arrival of many new players—conspired to produce enormous flux in precisely the realms that we were examining.

Some union leaders are thrilled to wield that cudgel against our report, even terming it “laughable” and “silly.” AFT President Randi Weingarten said it appeared to be “deeply flawed and misleading” and faulted it for omitting poverty in the analysis. (She didn’t say whose poverty. The states’? The kids’? The teachers’? We did, in fact, examine the resource levels of state unions themselves.)

But of course they wouldn’t like it. They don’t want to be studied or compared. They go to great lengths to conceal information about the means by which they wield power. If they lauded our analysis, you would and should be suspicious of it.

In the end, we learned a ton from it—about individual states, about national patterns, about unexpected relationships, and about surprising exceptions. The report itself provides vast detail and is worth examining, but here are a few highlights:

• As the map shows, and as you likely expected, the strongest unions are generally found on the West Coast, in the Northeast, and in the industrial Midwest; the South is mostly the province of relatively weak unions. But there are surprises. Hawaii, currently perched on the edge of a teacher strike, might be unknown to many as union-central. Likewise, Montana and Alabama punch well above their reputational weights.

• Thirty-two states require local school boards to bargain collectively with their teachers, fourteen states permit local boards to do this, and five states prohibit collective bargaining altogether (Georgia, North Carolina, South Carolina, Texas, and Virginia).• Teacher strikes, like the one recently concluded in Chicago, are legal in fourteen states and illegal in thirty-seven.

• Twenty-three states are “right-to-work” states, meaning that they prohibit unions from collecting “agency fees” from non-members. Twenty-eight jurisdictions allow such fees.

• In the 2010 election cycle, teacher unions in twenty-two states were among the top ten overall donors (excluding individual donations) to candidates for governor, legislature, high court, and elected education positions. In twenty-one states, they were among the top five highest-giving interest groups. In Colorado and Indiana, they ranked first.

• In just two states (Pennsylvania and New Jersey) did our survey of insiders unanimously deem teacher unions the most influential entities in shaping education policy over a recent three-year period. But survey respondents in twenty states found them to be generally more influential than other entities (including the state school board, state superintendent, governor, legislators, business interests, and advocacy groups).

• Despite all of that, the unions’ influence may be waning. For the three years prior to 2011, education policies in most states reflected union priorities. But in 2011’s legislative sessions (after 2010’s historic Republican surge), a growing number of lawmakers enacted policies that were less in line with union priorities.

We could not systematically link our rankings of union strength to state-level student achievement. Only a few of our data points (like teacher-employment policies) are apt to affect achievement directly. Others, like spending on education, could “touch” students indirectly, but there’s no strong evidence to support their link to achievement. We also have a timing problem since many state policies are in flux and don’t align with point-in-time snapshots of achievement. More important, we know that many other factors at both the state and local levels—poverty included, Randi!—affect how much and how well students learn, so postulating a relationship between state-level union activity and student achievement would be an oversimplification.

Having said that, we can’t resist eyeballing whether policies in a few high-performing states are more in line with the positions of reformers or of teacher unions. Take, for example, Delaware, Massachusetts, and Maryland. These three states, which, along with Florida, have significantly outpaced the rest of the country in student-achievement gains since the early 1990s, are often viewed as bastions of union influence. To be sure, they all have lots of unionized teachers. But when union strength is considered more holistically, these states show up toward the middle of the pack (nineteenth, twenty-first, and twenty-third, respectively).

No, we can’t claim that weakened unions alone will result in student-achievement gains. Still, suffice it to say that no one can claim with a straight face: “Want to boost student outcomes? Empower the teachers unions!” Which means, to our eyes at least, that what groups like Democrats for Education Reform, Stand for Children, and StudentsFirst are doing to challenge the hegemony of the unions is appropriate, important, and good for the country.

-Chester E. Finn, Jr. and Mike Petrilli

This blog entry first appeared in the Fordham Institute’s Education Gadfly Weekly.