"It's unbelievable to me that people's lives and relationships are literally being voted on in a matter of days," Pitt said in an email sent to HRC supporters. "In Maine, Maryland, Minnesota and Washington, voters will go to the polls to decide if gay and lesbian couples - our friends and neighbors - are worthy of the same protections as everyone else."
"This is our last chance to make a difference," he added. "If you're like me, you don't want to have to ask yourself on the day after the election, what else could I have done?"
It is not the first time that Pitt donates for marriage equality. In 2008, he had already donated $100.000 to fight against prop. 8.