I’m going to disagree with the general consensus here that there has been no decline in the effectiveness of protest marches as a tactic since their use in the 1960s.
In the early 1960s, the general population, the police, and the cohort of elected and appointed government officials as well were all unused to American citizens taking to the streets. It was startling and disruptive. It was also courageous. No one on either side knew what might happen next. It was a live confrontation that could go in any of a multitude of different directions.
By the middle 1980s it had become a pro forma ritualistic performance. You announce you’re going to do a protest (and everyone who might participate knows that that entails). You arrange the buses and make the signs, reminding everyone of the official police stance on what is an OK versus a not-OK physical formation for a protest sign, reminding everyone of what kind of ID to carry with them, asking those willing to be arrested to identify themselves in advance and reminding them of what factors (e.g., unpaid tickets, expired licenses, questionable citizenship status, bench warrants etc) should disqualify them from doing that, and what things to bring (license, paper printouts of contact info, appropriate amounts of cash for bail as need be) and leave behind (pocketknives, scissors more formidable than this, magic markers wider than that, pharmaceuticals not in original containers, illegal drugs), and so on.
Your march organizers inform you that 600,000+ people have shown up for the march. CBS estimates 300,000 and gives your march 2 mins 37 secs on the evening news including snippets with a spokesperson speaking to a reporter. That plus a brief moment of you marching folks showing a few signs and hearing you chant “What do we want? Blahh Blaah! When do we want it? Now!” which might as well be “four legs good, two legs bad”, you aren’t explaining your cause in any significant detail.
The police come up courteously: “OK, so remind me what cause are you folks marching for? Yeah Ok this is how we’ll do it, we’ll tell you to disperse. Those who want to get arrested stay, the rest of you will need to leave. We’ll tell you a second time and if no one moves we’ll assume those remaining are the ones who want to be arrested. Any questions?”
The “handcuffs” are plastic tie strips and the procedure at the jail and bail are all standard procedure.
No elected politician, average citizen, or business owner in the area is concerned about your contingent of marchers aside from delays in traffic patterns and the possibility of you littering or something.
You spend all day doing this and you go home trying to convince each other that you “DID SOMETHING”, that you stood up.
In the houses you drive past on your way home, someone says to their companion, “There was a protest march today”. Companion yawns. “Yeah? What this time?” “Blah blaah”. “Oh that. I’m sort of in favor. Oh, hey, did I tell you I got 200 points higher than ever before in Kandy Krush Saga?”
The damn things are boring to be in, boring to watch, and they aren’t educating anyone. Their time has come and gone and we need new ideas.