Social media is just one 'propaganda center' to be concerned with.

Hollywood is a notorious mouthpiece for politics. (They are also very heavy-handed in controlling the message through use of carrot-and-stick.)

Big media is of course totally lopsided, one way or the other. Fox is as bad as CNN is as bad as MSNBC. Take your pick.

For my tastes, the best way to get a central view is to look at a site like 'Real Clear Politics', which shows the most outrageous headlines from both sides of the aisle. The reader is left to triangulate a position, after having seen the most persuasive arguments from both sides of the aisle.