US Politics
There's a reason that the first Amendment tin the 10 that make up the Bill of Rights includes "the right of the people peaceably to assemble, and to petition the Government for a redress of grievances."
Protests are powerful because, like voting, they clearly show the will of the people, and the US was founded on the idea that the government is the expression of the will of the people, not the whims of officials.
And it is heartening for those who participate in the protests to see that they are not alone, that others share their concerns and energy. See for yourself: