What were the social/legal mechanisms for resisting imperial propaganda in the 19th century US?

Clearly all monarchic empires commanded a great deal of resources in the 19th century.

The US had a wide variety of voices expressed through various printed media. But I don't think there were any dominant ones.

How did the US manage not to be pulled into every European war of the 19th century?

Certainly having an industrial ally with a large capacity to produce food and weapons would have been a great advantage to any of the European powers. Did the European monarchs not try to bribe any of the politicians in the US? What social/political mechanisms prevented the US from being corrupted into support of any one of the European crowns or republics?