Editor's note: The following report is the third in a series about the massive online effort earlier this month to organize protests around ballot initiatives in California and elsewhere to ban same-sex marriage.

The protests against the Proposition 8 in California (and similar resolutions in Arizona and Florida on Election Day) took just over a week to organize. From November 7, when the planning started, over one million people received the message about the rallies on November 15. The experiences of the organizers and participants offer a lesson to other social and political groups interested in mobilizing large numbers of people in a very short time.

It's worth exploring further how word got out so quickly. National organizer Amy Balliett and local Chicago organizer Patrick Livingston are convinced that the success of the rallies was due to Internet tools. I wanted to see how ordinary participants learned about the rallies and were mobilized to participate, and asked attendees about how they found out about the event and whether they also relied on Web tools to organize friends.

Lindsey Padgett Brown attended the San Diego rally. She told me that she's been involved in a small "grassroots-style" group in the North County suburbs of San Diego, and found out about the rallies via a friend's posted item on Facebook. She researched details about the San Diego rally and passed it along to her group via email, organizing their participation in two days. She agrees that the Internet was crucial to the day's success:

"I don't think it could have been done without jointheimpact.com. [It gave us] one central location to find out what was going on and when it was happening in each city. Then, [you could] Email your friends and decide how to arrange it. Without the Internet, probably nothing of this magnitude could have happened so quickly."

Tim Moerke, who attended the rally in Minneapolis, Minnesota, had a similar experience. He attended with his wife, sister-in-law, and a friend, and was able to gather his small group in less than a day. Moerke believes that the Web tools made it easier for people to organize, which in turn makes them more likely to participate:

"I don't think either would have been nearly as successful without them. The social networking tools not only provided a central source of information that could be added to and changed as needed, they also informed quite a few people about the event who would be interested but otherwise might not have known all the logistical details -- where to go, how long it would be, what exactly would happen at the rally, and so on. People still could have found out all this if they really wanted, of course, but it would have been more work. The easier you make it for people to get involved and participate in causes and organizations, the more likely they are to do it."

Robyn Greenspan, a Connecticut resident, was actually visiting New Orleans when she learned of the protests through Twitter. Away from her usual group, she found information on the rally from a local Facebook group, communicating with people she'd never met:

"I was able to ascertain the NOLA location within moments of seeing the Twitter. I was also able to quickly Google map it to see how close the event was to my hotel.

"It is mind-boggling to think that this was organized on a national level in about 10 days and this certainly wouldn't have happened had we relied on traditional media or 'old school' networks. Events like these--organized electronically and spread virally--and the success of Obama's social networking reach has heralded a new era and a demographic shift in how information is disseminated and used as an influence."