One of the most enduring questions in the study of American politics is this: Do interest groups promote democracy by representing the views of their constituents before government, or do they distort democracy because such representation is skewed in favor of those with great resources?

In her important and ambitious new book, Local Interests, Sarah Anzia addresses this question squarely, offering a new approach to measuring the impact of interest groups. By comparing which types of groups are successful on what types of issues, a determination can be made about the relative level of interest group influence among those organizations lobbying the government.

Anzia’s focus is on local government. She argues that “research on local politics has tended to ignore interest groups, and research on interest groups has tended to ignore local government” (p. 3). She begins with an assumption, correct in my mind, that the research frameworks used to study interest groups in Washington are not well suited for studying urban politics. The smaller scale of city governments and the much-smaller universe of active interest groups, gives lobbies in these locales greater access to policy makers than is the case in Washington. The partisanship and polarization of national politics is generally not as fervent in the context of urban government.

Local Interests builds on a methodological approach focused on public policy as a dependent variable. The key is to measure change over time across different policy realms. Anzia criticizes interest group scholarship for tending to focus on a snapshot in time rather than longitudinally. As she points out, “interest group influence on policy often happens slowly, gradually, and incrementally” (p. 39). A typical snapshot study of interest group influence in Congress, Anzia notes, will not account for interest group influence that has already been exerted and manifested in whatever current policy is in place at the time the research starts. If business lobbies block an effort to strengthen clean air policies, their influence is reflected not just by what they did in this specific effort but also on what they had been doing over decades to shape the existing policy.

To capture more fully interest group influence, Anzia designed her study so that it could account for variation in interest group advocacy and impact across many different units of government. Thus, cities offer an appropriate laboratory as they vary so significantly in so many different ways. Although cities may be populated by the same basic types of advocacy groups, those organized interests will vary considerably in levels of activity, competence, and opportunities for influence. In short, cities offer a great deal to compare.

The primary database for Local Interests is Anzia’s own City Interest Groups Survey, which is composed of responses from elected officials in 515 US municipalities. Her sample was stratified by size so that small cities would not predominate as they would in a completely random draw. In the ensuing analysis, Anzia is careful to test whether size is a factor in the patterns observed. Two other original surveys, one of candidates for office in cities in nine different states, and the other of interest group campaign contributions for municipal elections in Washington and South Carolina, round out the empirical investigation.

This rich database yields a rigorous and nuanced assessment of urban interest groups. Anzia focuses on businesses, municipal unions, environmental groups, and neighborhood associations. Across a range of issues she documents when and how different interest group sectors are influential. Not surprisingly, mobilization is key. For example, police and firefighter union advocacy is positively related to city spending on compensation.

Local Interests is a resolutely statistical work, as Anzia harnesses the power of her large database to map out the interaction between lobbies and city governments. There are relatively few examples in her text and the pulse of city politics seems largely absent. The one extended example, a discussion of spending politics in West Covina, California, strengthens her discussion of municipal unions.

Anzia’s careful statistical analysis demonstrates the value of her approach, measuring impact on policy across lobbying sectors and cities. At the same time, her criticism of extant interest group scholarship strikes me as a bit harsh. I believe we’ve learned much about interest group influence from a variety of methodological approaches. Some of this work is qualitative and some quantitative. And certainly not all of it falls under the time frame of a snapshot.

Anzia does not shy away from addressing the overriding normative question about interest groups and democracy. The breadth and depth of her empirical analyses give her a credible foundation for making such a judgment. Her point of comparison is nothing less than Robert Dahl’s magisterial and endlessly controversial Who Governs? (1961). She does not say she has replicated Who Governs? but the intellectual roots of her work are evident. Dahl made his assessment of interest groups’ influence in New Haven, Connecticut, on the basis of their advocacy in three areas: urban redevelopment, political nominations, and public education. Anzia also looks at business growth and elections, while swapping out public education for police and fire unions. (School districts do not necessarily have the same boundaries as their parent cities.)

At the end of her book, on the next to last page, Anzia directly addresses Dahl. Like Dahl, she finds that advocacy groups influenced the policy sectors they cared about but not others. Dahl says this dispersal of power is the central characteristic of pluralist democracy in America. Anzia firmly rejects this: “[U]nequal power in one issue area does not neutralize or counteract unequal power in another area. It simply means that power in both areas is unequal” (p. 276). What then can we say about “who or what has power in American society”? Her conclusion is, “[i]t depends” (p. 277). That might not be a terribly satisfying answer but I think it is the correct one.