Large American cities are usually run by Democrats, but a few have Republican mayors. I’m interested in whether large cities with Republican mayors are safer than those with Democrat mayors and if so, why.

In a previous post, I looked at violent crime rates in big cities. My sample included all the cities with Republican mayors on Wikipedia’s list of mayors of the 50 largest cities in the US, of which there were ten. I also chose ten cities with Democratic mayors from the Wikipedia list. After choosing all 20 cities for my sample, I looked up and averaged their violent crime rates over the period of 2019-2021, using data provided by the Major Cities Chiefs Association.  I found that big cities with Republican mayors had lower violent crime rates than those with Democratic mayors. However, this doesn’t necessarily mean Republican-led cities had better crime reduction policies.  Crime rates are influenced by all sorts of things. But I’m interested in the impact of policy on crime rates, so that’s what I’m exploring – for now.

My process is to start with an outcome that varies by the variable of interest and then explore possible causal pathways from the variable to outcome. In these posts, crime rates are the outcome, mayor’s political party is the variable of interest, and the possible causal pathways are policies and their cascading effects. For example, if Republican-influenced cities were more likely to meet police staffing goals* than Democrat-led cities and they also had higher crime clearance rates and higher clearance rates were associated with lower crime rates, then we have a possible causal pathway. This is a gross simplification of course: whatever happens is likely the result of multiple interacting causal pathways. And even that is a gross simplification. I won’t elaborate further. Let’s just say it’s complicated. But complexity never stopped medical progress. Why should it stop progress in governance? Knowledge advances one baby step at a time.

So let’s check out the robbery crime and clearance rates of some big cities. Note there’s only nine Republican-led cities in the following chart (instead of ten, as in my original sample), because I could not find FBI clearance data on Jacksonville Florida.

Okay, the pattern is obvious - at least for these cities: Republican-led cities had lower robbery crime rates and higher robbery clearance rates than Democrat-led cities. Interesting pattern, but a pattern does not establish causality. Also, the above chart is a bit busy - it conveys so much information that it’s hard to see the connection between each city’s robbery and clearance rate. This one is clearer:

The apparent pattern still holds, though not in every case. For example, Miami has a pretty high robbery rate, but it’s robbery clearance rate is high as well. Perhaps Miami’s large tourism industry has something to do with its high-ish robbery rate. After all, tourists do make rather attractive crime targets.

But nothing here suggests that Republican-influenced policies are responsible for this pattern. Something besides policy might be driving the connection between mayoral political party, crime rates and clearance rates. Perhaps people who vote Republican are less likely to commit robbery but more likely to cooperate with robbery investigations - all leading to Republican mayors, lower robbery rates and higher robbery clearance rates. As I said before, multiple causal pathways.

Next: More patterns. Eventually leading to hypothetical causal pathways. Eventually leading to tentative policy suggestions.

* There’s actually little evidence that increased police funding or hiring alone results in higher clearance rates, but there are studies that find a connection between officer caseloads and clearance rates (LoFaso, 2020; Keel, 2011). Specifically, police units and bureaus with the lowest average caseload per officer tend to be the ones with higher clearance rates, at least for homicides. The International City County Managers Association has suggested police departments should have enough officers to follow the ‘Rule of 60’: 1) 60% of the sworn officers in a department should be dedicated to patrol staffing, and 2) no more than 60% of their time should be committed to calls for service. It’s important to remember, however, that optimal police staffing is only one piece to the puzzle of solving crimes. Just as important is the willingness of witnesses to come forward.

References:

Keel, T. G. (2011). Detecting clues in homicide management: A homicide “best practices” research project. Federal Bureau of Investigations, National Center for the Analysis of Violent Crime, Washington, DC. 

LoFaso, Charles A. "Solving homicides: The influence of neighborhood characteristics and investigator caseload." Criminal Justice Review 45.1 (2020): 84-103. https://doi.org/10.1177/0734016819874395

Response Times, Caseloads, and Clearance Rates: Informational Report/ Metro Nashville Police, 2023