Clearly, something else is driving crime rates. Interesting, though that the steep decline in violent crime tracks Bill Clinton's welfare reforms.
How Bill Clinton’s Welfare Reform Changed America
No. Clinton actually got his welfare reforms passed after Gingrich became Speaker. Remember, that Gingrich was so opposed to the plan that he shut down the government to force Clinton to drop it? And it was only after pretty much everyone took Clinton's side that Gingrich folded.
I'm just pointing out that the number of single-parent families has grown while crime has dropped dramatically. That's not proof that single-parent families prevent crime, but it is proof that crime is not caused by single-parent families. As you know, there
is a strong correlation between poverty and crime, and since poverty declined after welfare reform, that might be the reason. Notice the decline in crime began about the time Clinton's welfare reform package was signed into law.
The idea behind the "war on poverty" was a good one, but structurally, it led to people becoming dependent on help. Clinton's approach was to limit welfare and to use incentives to get training and find jobs. It worked.
And that seems to have reduced the crime rate. A good result, I think.
And yes, there has been a "Trump bump" in violent crime in recent years:
Partially, it's the increase in right-wing terrorism (which is now the major domestic terrorism concern), but also due to an increase in hate crimes against minorities generally. It's not even close to the rates we had 20 years ago, though.