More than 300 news outlets are launching a campaign on Thursday to counter President Donald Trump's attacks and promote a free press.
The Boston Globe made the call last week for a nationwide denouncement of the president's "dirty war" against the media, using the hashtag #EnemyOfNone.
Mr Trump has derided media reports as "fake news" and attacked journalists as "enemies of the people".
UN experts have said this raises the risk of violence against journalists.
The Boston Globe had pledged to write an editorial "on the dangers of the administration's assault on the press" on 16 August, and asked others to do the same.
The initial positive response from 100 news organisations has grown closer to 350 with major US national newspapers and smaller local outlets answering the call, along with international publications like the UK newspaper The Guardian.
What have the papers said?
Starting with the Boston Globe itself, the editorial there, headlined Journalists Are Not The Enemy, argued that a free press had been a core American principle for more than 200 years
The New York Times chose the headline A Free Press Needs You, calling Mr Trump's attacks "dangerous to the lifeblood of democracy". It published excerpts from dozens more publications beneath
Thursday's campaign comes after a series of incidents and Trump remarks ramping up pressure on the media.
While Mr Trump's daughter Ivanka distanced herself from her father's media attacks, White House press secretary Sarah Sanders refused to say the media were not an enemy of the people.