At some point every year, it seems news organizations collectively report on the United States’ safest and most dangerous cities. Shortly thereafter, the unfortunate city to be tagged with that year’s “most dangerous city” award goes on the defensive, lambasting what it sees as a “misuse of statistical crime data.”

While cities with high crime typically display high unemployment, low average educational achievement, and high levels of poverty compared to those with low crime rates, one thing is certain of cities making the top ten: their populations are comprised of high percentages of minorities. However, does this hold true for the rest of the cities on the nefarious most dangerous list?

Background:

Since 1995, the annual publication entitled City Crime Rankings has been produced by Morgan Quinto Press until it was bought out in 2007 by CQ Press. Essentially, this publication is simply a regurgitation of the Federal Bureau of Investigation’s (FBI) annual statistical publication Crime in the United States. However, City Crime Rankings’ purpose—as described by its publisher—is to “. . .provide easy-to-understand crime comparisons for cities and metro areas throughout the United States.” It is from this publication that the infamous and controversial America’s Safest and Most Dangerous Cities ranking is derived.

In the listing, cities, which have populations in excess of 75,000 and report their crime statistics to the FBI, are ranked based on six categorical crime rates: murder, rape, robbery, aggravated assault, burglary, and motor vehicle theft. These crime categories are equally weighted and added together to calculate a city’s aggregate level of violent crime, then divided by its total population to create the violent crime rate used to create the lists’ ordinal ranking.

Although widely reported at its face value by nearly all media outlets, the outright ordinal ranking of entire cities from best to worst is controversial due to its often misleading perceptions of the danger or safety associated with a particular a city. In fact, the FBI, which produces the annual statistical data that the report utilizes, cautions against attempting to compare crime data of different geographical units solely on the basis of their population coverage. According to their warning, rankings such as with the City Crime Rankings publication “provide no insight into the numerous variables that mold crime in a particular . . . city,” and “lead to simplistic and/or incomplete analyses that often create misleading perceptions adversely affecting communities and their residents.”

Some key points of contention concerning the city rankings are the report’s indifference towards: individuals risk profiles (such as age and lifestyle); violent crime that is disproportionately concentrated in a few small areas; property versus bodily crime; and to the degree which suburbs are located within a city’s boundary line. The FBI also details some additional variables that can distort crime rankings.

The Data:

The racial and ethnic composition was found for the 100 most dangerous cities of 2006 from America’s Safest and Most Dangerous Cities. The numbers for the three racial groups examined were found from the U.S. Census Bureau’s 2006 American Community Survey. From this, percentages of “blacks or African Americans,” “whites,” and “Hispanics or Latinos (of any race)” were calculated for each city. The racial and ethnic classifications follow the Federal Register Notice, Revisions to the Standards for the Classification of Federal Data on Race and Ethnicity.

For the three racial or ethnic groups, and for blacks and Hispanics combined, each group’s percentage of total population is plotted for each city — from most to least dangerous. A line of best fit — or trend line — is then found to show the relationship between the ranking of the cities and their racial and/or ethnic groups.

Blacks as a Percentage of the Total Population for the Most Dangerous Cities:

In terms of the most dangerous cities and black populations, a correlation of .5427 between blacks and crime was found with an R² of 29.45 percent. This means that for every increase in the ranking of a city as more dangerous, the black population variable would explain 29.45 percent of the change.

The slope of the trend line is -.003610. Thus, for every increase in a city’s “danger” ranking, the black population percentage increases by .3 percent on average.

Hispanics as a Percentage of the Total Population for the Most Dangerous Cities:

A slightly negative correlation of -.0416 was found between Hispanics and crime. However, the results were not statistically significant from zero.

Blacks and Hispanics as a Percentage of the Total Population for the Most Dangerous Cities:

Combining Hispanic and black populations together actually decreased the correlation compared to blacks’ correlation singularly. Correlation decreased by .0199 to .5228 – R² decreased by 2.12 to 27.33 percent.

Whites as a Percentage of the Total Population for the Most Dangerous Cities:

A negative correlation of -.5607 was found between the white population of a city and its crime ranking. The absolute correlation between crime and city rankings for white populations was slightly higher than for black populations. That means an increase in the percentage of whites within a city has slightly more of an impact on decreases in crime rankings than does a decrease in the percentage of blacks.

The slope of the trend line was a positive 0.003469. This is nearly a perfectly inverse slope of the black population trend line. A close to perfect inverse relationship exists between black and white populations and a city’s crime ranking. Stated another way: For every increase in a city’s “danger” ranking, the percentage of black population increases by 0.36 percent while the white population decreases by 0.35 percent.

Sadly, I already knew of blacks' correlation to violent crime in the US. Although there are a many of variables that go into predicting whether a city has a high propensity for violence, no single variable predicts it better than blacks' percentage of the population. That, of course, in no way speaks to causation. Being black absolutely does not mean you are more likely to be violent. But it can be inferred that the long list of variables — including culture –  associated with causing violent criminal behaviour, is closely associated with a very large proportion of America's black population when compared relatively to other ethnically or racially defined US populations.

I was surprised though to find the statistically insignificant correlation to violent crime and Hispanic population, alone. The broad stereotypical thought is that areas with high concentrations of minorities are predictably more violent. However, in examining the cities in this top 100, we find that Hispanics are not a predictor of violent crime at all. In fact, when included with blacks in the regression, the coefficient of determination actually decreased.

So, the answer to the question of whether or not minorities comprise high percentages of the populations for the rest of "America's most dangerous cities" is yes for the vast majority, excluding a couple outliers. But more specifically, the data suggests that, in general, blacks' percentage of a city's total population predicts a city's ordinal ranking of violence, possibly better than any other single variable's influence.