"The essence of a hackathon is really that great ideas can come from anywhere. It doesn't have to be someone who is running a company, it doesn't have to be someone who is a citizen of a country," said Zuckerberg.
He spoke to a room full of not just programmers, but dreamers.
"A dreamer -- and there's about two million of them in the United States -- is somebody whose parents brought them over to the country, they're undocumented, they were brought over as children, they've grown up here, but all these barriers are put in their way," said Joe Green, the Fwd.Us founder.
So Green teamed up with Zuckerberg and the co-founders of Dropbox and LinkedIn to bring those dreamers to the hackathon from all over the country. The young programmers are all undocumented immigrants.
"I realized that no matter how talented I am, I couldn't do the internship at Goldman Sachs, I couldn't even intern at the UN, and follow my aspirations and I hit the ceiling, so I became really frustrated," said Rocio Lopez, a hackathon participant.
Lopez did go to college, but she was lucky. Zuckerberg's focus on immigration started when he was teaching a group of middle schoolers. He told the group, "And one of the top students put his hand up and said, 'I don't think I'm going to be able to go to college because I'm undocumented' and it just blew my mind."
So the Hackathon is about using technology to find solutions, everything from a social network just for dreamers to tools for contacting Congress, with 24 sleepless hours to put them all together.
"People would be shocked at what you can accomplish in 24 hours. And I think our friends in Washington can take note of that," said Drew Houston, the founder and CEO of Dropbox.
The young coders in the room only slightly outnumbered the people with cameras and that's on purpose. The organizers want this event to get lots of attention.
"This is kind of like the other side of the story. This is who we really are, like we're education students who want to help our country and want to make, create jobs for our country and be prosperous here," said Sarahi Espinoza, a hackathon participant.
Espinoza got emotional when she spoke to the group. She said, "I am one of the millions of undocumented people in this country whose family is separated due to the immigration system."
It's been eight years since she's seen her mother.
Zuckerberg says he's fighting for people like her. He said, "I think this is one of the biggest civil rights issues of our time."