A social media friend of mine made a cogent and insightful observation about Donald J. Trump’s behavior and his comments about the state of affairs in certain Democratically run American cities.

Here is what my friend posted on Facebook: Things that make you slap your forehead. Why has Trump attacked the mayors of Baltimore, Chicago, Detroit and Atlanta for crime, vermin and housing, but not the mayors of New York, Philadelphia, or Los Angeles? They are all Democrats. What could it be? Look up their photographs, as I did.

What is my friend’s point?

It’s as clear as it gets. The mayors of Baltimore, Chicago, Detroit and Atlanta are, um, African-American. The mayors of NYC, Philly and Los Angeles are white.

My friend might be mistaken, though, on whether the president has been stone-cold silent about LA’s problems. I believe his point, though, is well-taken, in that Donald Trump — at best — spends relatively little emotional energy blasting white Democrats while unloading heavily on those Democratic politicians who happen to be people of color.

Is that the act of a racist politician?

Wasn’t it the comedian Arsenio Hall who used to poke fun at those things “that you make you go … hmm”?

This trend, though, ain’t funny.