The idea that the "Medium is the Message" is proven to be an interesting observation in this case. Protesters invoked their first amendment right to assemble and express their discontent with their government, which is a right guaranteed by this democratic government. The medium in this case is the use of marches and assemblies to express their views via rhetoric, instead of coercion, which the protesters are accusing the Trump administration of promoting. What these marches really are could be thought of as a conversation between the protesters and the Trump administration in which rhetoric is being exchanged by marches, demonstrations, press releases and executive orders rather than oral debates as was common at the Agora in Ancient Athens (supposedly).
Source: Hartocollis, Anemona. "Women's March Highlights as Huge Crowds Protest Trump: "We're Not Going Away"." The New York Times. The New York Times, 21 Jan. 2016. Web. 1 Feb. 2016.