The irony of having large marches in most of the major cities of America is that most of these cities voted for Hillary. Our cities are and long have been overwhelmingly Democrat. But most of the land area, and most of the people in this country, do not live in our largest cities. They will not see these marches, and for his part Trump is well aware that this is smoke and mirrors designed to give our complicit media ammunition to do yet more ineffective lying.
It will feel GREAT for those involved. They get to feel like they did something. They can slap each other on the back. But it is a fundamentally solipsistic enterprise. They are not changing any minds at any level of our body politic. In fact, most of us who voted for Trump are sick and tired of their loser bullshit. We wish they would keep their fucking word, accept that they lost an election they would have won if they had any useful fucking ideas at all, and stop pretending that the entire political world does and should revolve around their patent childishness, ignorance, intolerance, violence, and narcissistic pouting.