Are Protest Marches Effective?

Marching is a clearly defined collective act of the people! It's proof that in a free country you can do something to get your voices heard by the elected officials you are allowing to serve you, to do what needs to be done for the good of all the people. 

Or at least... get them to think about it. 

Also, sometimes if you write letters, they might get lost in the mail or never even delivered. It's kind of difficult to ignore a large mass of people all moving together coming at you. :)