New York (CNN Business) More than 300 Vox Media employees staged a walkout on Thursday as staffers and management failed to come to an agreement for a union contract after more than a year of negotiations.

The walkouts affected Vox Media's group of popular websites -- such as Vox, SBNation, The Verge, Eater, Recode, Curbed, and others -- and some were not publishing new content on Thursday.

"Our unit members are taking their sites dark today to show management how important these issues are to us," tweeted the account for the Vox Media Union.

Another tweet included several photos of an empty newsroom with union posters that said "Contract Now!" on walls and computer screens.

The Vox Media Union has walked out today. Here's what it looks like in the New York office. pic.twitter.com/erPp4fW1nw — Vox Media Union (@vox_union) June 6, 2019

Jason Gordon, the director of communications for the Writers Guild of America East, which is representing the staffers, told CNN Business that the walkout was a sign of unity.

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