I already mentioned that northern states had union-busting squads who formed the basis of modern police forces, so yes, I'm aware of Boston, too.
Once again, you use that word. I agree that it's ridiculous to compare today's policing to anything like historic policing or ancient slave patrols. Today's police are far less accountable, more violent, and heavily armed.
Within the great city, there were, as you pointed out, police. As I pointed out, they were mostly there for fire-fighting and as a slave patrol, and were themselves made up of mostly-slaves. But you might be thinking, what about investing crimes? That's what police do when there aren't traffic stops to make, right?
In that great city, if you wanted a crime investigated, you did it yourself. Evidence gathered? Find it yourself. If you wanted to accuse someone of something, you grabbed them and at least one witness and dragged them before a judge. So justice, what there was of it, was largely available to the wealthy, who could afford to hire people to drag other people before judges, and if you were a poor person wanting to accuse a rich person of a crime, well, good luck with that.
So modern cops might have a really poor clearance rate for most crimes, barely exceeding half even for murder[0], but at least they try, which is more than can be said for Roman vigiles urbani. And at least they pretend to be impartial, even if one can clearly see that crimes are prosecuted unevenly, and that US prisons are filled with more than their fair share of the poor.
0. https://www.statista.com/statistics/194213/crime-clearance-r...
