The editorial staff of digital news site ThinkProgress has become unionized by the Writers Guild of America East — the fourth such digital outlet to come on board to the WGA in recent months.

The guild and the news outlet, housed at the Center for American Progress Action Fund, announced Wednesday that the fund has agreed to voluntarily recognize the WGA East as the collective bargaining representative of its editorial staff.

The ThinkProgress editorial staff — which numbers about 30 — unanimously supported the unionization effort. In a letter to management informing them of their intention to organize with the guild, the staff said both ThinkProgress and the Center For American Progress Action Fund have “long publicized the many benefits of unionization for individual workers, the middle and working class, and the economy as a whole.”

“Here at ThinkProgress, we believe having a union will help us protect and elevate the good conditions we currently enjoy in our workplace, both for ourselves and for all who come after us,” the letter said. “This security will ensure we continue to create the cutting-edge, high-quality, and editorially independent journalism ThinkProgress is known for long into the future.”

The WGA East has organized Gawker, Salon and Vice in recent months and the American operation of the British newspaper The Guardian recently organized through the NewsGuild-CWA. “We’re proud to be part of this moment and this movement in our industry and hope our participation helps digital media workers everywhere,” the letter said.

Lowell Peterson, executive director of the WGA East, said, “The men and women who write, edit and produce stories at ThinkProgress join hundreds of others in digital media who recognize the power of collective bargaining. They are committed to working together to build sustainable careers crafting stories that are honest and insightful. We welcome ThinkProgress to the Writers Guild of America, East.”