If our friends on the left are going to look at what's going on after tax reform in Kansas and declare it proof positive of the utter failure of Republican economics writ large, surely the news of recent weeks makes it worth considering which party has been running Baltimore's police, Detroit's economy and -- ahem -- Atlanta's schools .

At National Review, Kevin Williamson does just that :

"American cities are by and large Democratic-party monopolies, monopolies generally dominated by the so-called progressive wing of the party. The results have been catastrophic, and not only in poor black cities such as Baltimore and Detroit. Money can paper over some of the defects of progressivism in rich, white cities such as Portland and San Francisco, but those are pretty awful places to be non-white and non-rich, too: Blacks make up barely 9 percent of the population in San Francisco, but they represent 40 percent of those arrested for murder, and they are arrested for drug offenses at ten times their share of the population. Criminals make their own choices, sure, but you want to take a look at the racial disparity in educational outcomes and tell me that those low-income nine-year-olds in Wisconsin just need to buck up and bootstrap it?

"Black urban communities face institutional failure across the board every day. There are people who should be made to answer for that: What has Martin O'Malley to say for himself? What can Ed Rendell say for himself other than that he secured a great deal of investment for the richest square mile in Philadelphia? What has Nancy Pelosi done about the radical racial divide in San Francisco?"

Read the whole thing , but don't stop there. For all the hand-wringing about income inequality in cities such as Baltimore and Atlanta, it is highly relevant to consider that the party making the biggest fuss about the issue is the one that has dominated politics in these cities for decades.

I'm reminded of a piece in The Atlantic last fall in which Derek Thompson reviewed research about the nation's 100 largest metro areas by Jed Kolko, the chief economist for Trulia.com. Kolko found inequality tends to be worse, and housing less affordable, in metro areas where Barack Obama's 2012 margin over Mitt Romney was at least 20 percentage points. The reverse was true -- that is, income was more equal and housing more affordable -- in areas that went for Romney.

Wrote Thompson :

"'All homeowners have an incentive to stop new housing,' Kahn told me, 'because if developers build too many homes, prices fall, and housing is many families' main asset. But in cities with many Democrats and Green Party members, environmental concerns might also be a factor. The movement might be too eager to preserve the past.' ...

"I asked Kahn if he had a pet theory for why liberals, who tend to be vocal about income inequality, would be more averse to new housing development, which would help lower-income families. He suggested that it could be the result of good intentions gone bad.

"'Developers pursue their own self-interest,' Kahn said. 'If a developer has an acre, and he thinks it should be a shopping mall, he won't think about neighborhood charm, or historic continuity. Liberals might say that the developer acting in his own self-interest ignores certain externalities, and they'll apply restrictions. But these restrictions [e.g. historic preservation, environmental preservation, and height ceilings] add up, across a city, even if they're well-intentioned. The affordability issue will rear its head.'"

My emphasis there at the end. You have probably heard of the magic of compound interest for money and investments. In cities across America, we are seeing the compounding effect of left-wing governance going unchallenged over a span of decades, culminating in the deep-seated problems that now spark protests and riots.

The irony is that the rioters in Baltimore and elsewhere aren't marching on city halls or setting fire to public offices to show their anger (though they have, in many cases, set fire to police vehicles). Instead, they're attacking the very private businesses and property that left-wing governance has choked to the point of being unable to offer an alternative model for opportunity and prosperity.

As long as the targets of the rioters' anger make it obvious they're intent on carrying out "not a revolt, but a crime spree," as Williamson aptly puts it , it's clear they have no interest in identifying the source of the systemic oppression they talk about. This also gives the lie to radical calls to eschew non-violence, or to view appeals to non-violence as a "ruse," on the premise that the real source of violence and aggression lies within unreformed public services -- when these services are of course run by public officials who generally occupy the same space on the political spectrum as the writers.

All of which makes it sadly likely we will see more explosions like the one in Baltimore, not fewer.