Reading that headline, you might assume that confidence in cops is down among the general population too. Not so. It’s up five points since 2015. What Gallup’s seeing isn’t erosion in trust for the P.D. among Americans overall but starker polarization among different demographics — red/blue, white/black, young/old. In this as in so much else, the country’s pulling further apart.

The surface here is still but the water underneath is churning. The share of Americans who say they have a “great deal” or “quite a lot” of confidence in the police:

Scan that 2012-14 column and marvel at how similar the numbers are across various groups. Blacks are the conspicuous outlier, which is no surprise given the history of police relations with African-Americans, but liberals, moderates, and conservatives are all within eight points of each other. Different age groups are clustered even more tightly, with a mere five points separating the 18-34, 35-54, and 55+ demographics. Even liberals are north of 50 percent support.

Then came the summer of 2014 and the Michael Brown and Eric Garner killings, never mind that the Obama Justice Department cleared the officer who shot Brown of wrongdoing. Sensational cases of police violence against black suspects have followed sporadically — Tamir Rice, Freddie Gray, Alton Sterling, Walter Scott, and most recently Philando Castile — interspersed with sensational attacks on the police themselves, most famously in Dallas and lately with NYPD Officer Miosotis Familia. Result: The eight-point spread among ideological groups three years ago is now a 28-point spread. The five-point range among age groups is 19 points, and the 12-point difference between Democrats and Republicans has more than doubled.

The most interesting downturn is among Hispanics. Black confidence in the police was already so low that it didn’t have much further to fall but Hispanic confidence was notably high in 2012-14, several points above the national average. Three years later Hispanics are nine points below that same average and 14 points(!) below their previous level of support. Between that and the falloff among the 18-34 group generally, the fate of relations between cops and the civilians they’ll be charged with protecting in a changing America feels … uncertain, shall we say.

Of note, by the way: Overall public confidence in the police has never dropped below 52 percent over the past 24 years of polling. Support within groups varies widely, as we’ve seen, but the basic public trendline doesn’t budge that much apart from occasional spectacular events. (Confidence in the police shot up after 9/11.) Presumably that’s evidence that opinion on this subject is always polarized ideologically. When things happen to turn the left against the cops, the right rallies to their defense. The result is a deceptively stable level of confidence among the general population.