Underneath the clash and clang of controversy over presidential impeachment, public policy and personal initiative can slowly and seemingly imperceptibly improve life in America. That was the case two decades ago, amid the swirling arguments over the mostly party line impeachment of then-President Bill Clinton and the Senate’s mostly party line refusal to remove him from office.

This 1998-99 controversy occurred as conservative welfare and crime control reforms were vastly reducing — far more than their advocates had expected — welfare dependency and crime control in America’s central cities.

These reforms were pioneered by then-Wisconsin Gov. Tommy Thompson and then-New York Mayor Rudy Giuliani and advanced mostly by Republicans but also by many Democrats. The Clinton 1994 crime package helped marginally, and then-House Speaker Newt Gingrich successfully pushed federal welfare changes through Congress, which Clinton, after vetoing two versions, finally signed.

Today, beneath the clamor, one can find evidence of unexpected improvement. During the Trump presidency, manufacturing and blue-collar wages are up; income inequality is lessening; unemployment among blacks and Hispanics is at record lows; disability and food stamp rolls are sharply down; and non-college-graduate whites are making more economic gains than more educated whites.

All these trends are reversals of trends most experts thought would continue indefinitely. They look like fulfillment of President Trump’s campaign promises and suggest that his policies — the tax cuts, trade protections, discouragement of low-skill immigration — have succeeded more than most predicted. Other things may have contributed — Obama policies, as some Democrats argue; the almost total end of low-skill Mexican immigration in 2007-08; and reduction in jobs offshored to China.

And something else, which has been widely ignored: “black Americans have been making rapid progress along most important dimensions of well-being since the turn of the millennium,” as Columbia undergraduate Coleman Hughes wrote in his latest article in the invaluable online magazine Quillette.

From 2001 to 2017, Hughes points out, the incarceration rate for black men ages 18 to 29 dropped by more than 55%. In those years, the birth rate among black women ages 15 to 19 declined 63%. Black life expectancy increased by some 3.6 years.

From 1999 to 2000 and 2016 to 2017, the number of blacks awarded bachelor’s degrees rose 82%. A Federal Reserve survey showed 60% of blacks saying they are doing better financially than their parents.

Hughes notes that if you measure blacks’ achievements compared to those of whites, you might conclude that blacks are gaining ground. But he makes a powerful case for focusing on the improvements among blacks over time. We don’t usually compare improvements (or, as we have seen recently, deteriorations) of white Americans’ behaviors by comparing them to other groups but rather by comparing them to the same group in the past.

And by that measure, the improvements in black Americans’ — especially young black Americans’ — behaviors over the last generation have been astounding. They’re a refutation of the intellectual fashion in many quarters, set by writer Ta-Nehisi Coates several years ago, that blacks in an eternally racist America have always lived a nightmarish existence and always will.

Not so. The sharp reduction of violent crime and substance abuse among young blacks over the past 30 years resembles similar reductions among Irish immigrants and their children in the late 19th century.

How do we account for this enormous and beneficial change? It seems far from a coincidence that today’s young blacks grew up in an America shaped by 1990s welfare and crime reform.

There’s certainly evidence that children of single mothers do better when they see their parent as a self-sufficient working person rather than an idle welfare recipient. And it seems likely that adolescents growing up in neighborhoods with sharply reduced crime may be less likely to commit crimes themselves than those who came of age in the crack-infested neighborhoods of the late 1980s.

People tend to do what they think others expect, in two senses of the word: prescriptively (you should do this) and predictively (you’re likely to do this). The 1990s reforms set higher prescriptive expectations and produced higher predictive expectations. Barack Obama, with his professional competence and faithfulness to family, was surely a helpful role model.

The lesson is that no matter how nasty politics gets, life on the ground can get better, indeed much better, than almost anyone predicted, with help from good policies and motivated personal effort.