Consolidating city and county governments is an idea with intuitive appeal. In a country with nearly 90,000 units of local government, wouldn’t it make sense to combine some of them to reduce duplication of services and gain economies of scale? The boundaries of our cities and counties were established long ago -- centuries ago, in some cases -- for reasons that often have been forgotten. And many of the problems our governments face today pay no attention to political boundaries established when a day’s horseback ride might have determined the location of a county seat.

But while those who lead consolidated city-county governments believe that the benefits are substantial, the evidence is mixed, at least as far as spending is concerned. Kurt Thurmaier, director of the Division of Public Administration at Northern Illinois University, says that while the selling point is efficiency, that doesn’t happen very often. Sometimes, for example, only the major cities within the county are included, and when employee salaries and benefits within the combining jurisdictions are brought in line with each other, the rounding tends to be up, not down.

Things have worked out better for Kansas City, Kan., and Wyandotte County, according to Dennis Hays, who has been administrator of that unified government since it was created 17 years ago (and who before that was the city’s administrator for three years). Before the consolidation, he says, “we were slipping into the deep abyss, and if we hadn’t done consolidation when we did, who knows where we’d be?” Since then, he says, the quality of services has improved, thanks to economies achieved by combining duplicative departments. Taxes have been cut by 15 percent, and the combined workforce has been reduced by 20 percent. But in Hays’ view, having a single policy-making body willing to take on the tough decisions has made the biggest difference, resulting in real improvements to the local quality of life. “We are an older blue-collar community, and now we are seeing young people wanting to move into Wyandotte for the first time in decades.”

Nashville, Tenn., is in the process of celebrating 50 years of consolidation with Davidson County. Mayor Karl Dean, the combined government’s sixth mayor since consolidation, believes that the overwhelming majority of his constituents would see the merger as a key component of the success the city has had, including not experiencing the population exodus that a lot of cities have. In addition to efficient service delivery, Dean says, the consolidation has allowed Nashville to deal with issues such as economic development and securing sports teams without involving a lot of small political jurisdictions. And consolidation has provided a larger tax base, something that’s critically important in efforts to improve services while holding down costs. As another bit of evidence of the success of consolidation, Dean notes that once or twice a year someone from another city asks Nashville how to do it.

The answer, of course, is that consolidations are politically very difficult to pull off. Somebody has to give up power, and consolidations usually require a vote of the electorate in each of the combining jurisdictions. So it shouldn’t be surprising that there have been many more defeats than victories. Between 1921 and 1996, there were 132 formal consolidation attempts with only 22 successes, according to a history of consolidations by Pat Hardy of the University of Tennessee’s Municipal Technical Advisory Service. In the 1990s alone, there were 13 unsuccessful consolidation referenda votes.

Little wonder that many pundits keep declaring the idea dead. Yet it keeps coming up. Since 1805, when New Orleans combined with Orleans Parish, there have been 33 city-county consolidations, according to Hardy’s research, with about two per decade since World War II and four in the 1990s. The most recent consolidation was that of Louisville, Ky., and Jefferson County in 2003.

Consolidation is not a panacea, but in the end structure does matter. Where would New York City be today if it were still five separately governed boroughs? Marrying political sovereigns is hard, but no consolidated government has ever divorced.