Travel site on Tuesday announced it would back Referendum 74, the Washington state ballot measure which if approved would uphold a gay marriage law enacted by lawmakers.

“As the world's largest online travel company – with operations in well over 30 countries – we know firsthand that the world is a diverse place. Much like our customers, clients, partners, and suppliers, our employees represent a multitude of locations, cultures and experiences,” said Expedia President and CEO Dara Khosrowshahi in a statement released by Washington United for Marriage.

“We strive to actively promote equality in our workplace and are committed to treating one another with respect and dignity. … Today, we add our voice to the topic of marriage equality. We thoughtfully engage in this public discussion because it has significant impact on our employees, customers, and partners, all with whom we interact daily. Supporting the legislation recently passed in Washington State – which provides same-sex couples with the same right to civil marriage that opposite sex couples already enjoy – is a natural extension of our ongoing commitment to the LGBT community.”

Zach Silk, campaign manager for Washington United for Marriage, welcomed Expedia's endorsement.

“We are so pleased to add Expedia to our ever-expanding list of Washington-based corporate supporters,” said Silk. “Like other corporate leaders, Dara Khosrowshahi understands that treating all families fairly and allowing all loving couples the freedom to marry is a core value that builds strong communities and strong businesses. When most people think travel, they think Expedia and we couldn't be more excited to have them join our effort to Approve Referendum 74.”

The Bellevue-based online travel company said more than 2,270 of its 8,900 employees live and work in Washington.

Other Washington-based companies supporting marriage equality include T-Mobile USA, Starbucks, Microsoft and Amazon. Last month, Amazon CEO Jeff Bezos and his wife MacKenzie gave $2.5 million to the effort.

(Related: Microsoft's Bill Gates, Steve Ballmer support Washington gay marriage.)