The Benchmarking Mirage
Unless you live in Minneapolis or St. Paul, there is no such thing as a "twin city." Many governments are searching for a meaningful comparison, but it can be a frustrating path. The issues below highlight the reasons why finding an exact "twin" is a mirage - as soon as you find a good comparison, you realize there is more complexity to take into account. Instead of trying to find an exact match, find a cousin with a strong relationship to one specfic service area.
Thinking about Population
Population is a simple word with a lot of embedded complexity. Population volume, the number of people who live a jurisdiction, is important. However, comparing one jurisdiction to another based solely on the population volume is not enough. Population density, a measure of population volume per unit area, is also critical. For example, Chicago is America's third most populous city, but is the 14th in population density - so comparing Chicago to New York and Los Angeles based on population volume alone can disregard important differences in the distribution of people across geographic areas. Population demographics, quantifiable characteristics of a given population, also matter tremendously. For example, Phoenix and Philadelphia have similar total populations (between 4 and 6 million depending on what geographic boundaries you include). However, Philadelphia is four times as dense as Phoenix, and Phoenix has almost three times as many Hispanic residents as Philadelphia. Population fluctuations, changes in population over time, also matter. Some jurisdictions see huge increases in population during the workday, while others stay roughly the same. Some jurisdictions are losing residents while others are gaining them. Taking all of these population considerations into account makes it nearly impossible to find an exact jurisdictional comparison. So consider narrowing the scope of what you are trying to benchmark against. Instead, consider using other factors, which correlate to population, to find comparable jurisdictions. For example, find a jurisdiction with the same weather or geographic landscape. Look for cities with the same type of transportation infrastructure (i.e., highways vs. subways), or cities with comparable budget expenditures. These characteristics might be a more direct route to finding a comparable jurisdiction.
Thinking about Mobility
Mobility is a key driver of a jurisdiction's economy and population. Cities that are accessible through robust public transportation networks develop differently than those connected by motorways. The advent of car sharing and services like Uber are also impacting the way people move around a place. But just because two jurisdictions have a bus system, doesn't mean they are worth comparing. To find meaningful comparisons across cities with rail and bus systems, consider ridership differences, the number of lines and stations, miles of service, and fare differences. When thinking about highway-connected jurisdictions, think about its relationship to geopolitical boundaries, congestion, and urban sprawl. After all, benchmarking DMV services in a city where most people rely on cars should likely differ from cities where public transportation is the norm.
Thinking about Infrastructure
The United States is a young country, but the infrastructure varies widely and is aging at varying rates. Housing stock in the Northeast faces a different set of issues than housing stock on the west coast. Transportation networks were built at different times, with varying levels of reach into suburbs and across geopolitical boundaries. Technology is unevenly deployed across jurisdictions based on resources and proximity to academia and the tech sector. Building codes on the west coast focus on earthquake resiliency more than building codes on the east coast. Some jurisdictions have combined sewer/stormwater systems and others keep them separate. These infrastructure differences create important differences in the way services get delivered and should be taken into account when comparing one place to another.
Thinking about Politics and Governance
All politics is local, and that has a huge impact on external benchmarking. Jurisdictions have varying governance structures. Some have Strong Mayors and others have Strong Council/Managers. Some jurisdictions have Mayoral control of schools, others have an elected school board. Some cities deliver health and human services, while many cities reserve those services for the county governments. Some services are delivered based on political boundaries, others are delivered based purely on physical boundaries. For example, Chicago previously conducted trash collection by Ward while most cities pick up trash based on geography.