Why did CNN’s web site dominate inauguration coverage? Facebook Connect?

CNN‘s web site had the attention of more than four percent of U.S. web users when it streamed President Barack Obama’s inauguration live on Tuesday, according to a Compete traffic report today — much higher than rival Fox, CBS and MSNBC’s traffic combined. Why?

Maybe it was because CNN’s site was already much more popular, as you can see from the Compete traffic graph. Since most people already visited CNN’s web site for online news, its where they told their friends to go.

However, many of us were impressed by CNN’s integration of Facebook Connect (even though the video wasn’t perfect). Maybe that service’s success had something to do with the traffic increase? It basically lets you chat with your friends on Facebook while watching the inauguration on CNN, repurposing Facebook status updates feature into a real-time threaded chat service. Facebook said that more than 1.5 million status messages were generated on the CNN site that day. See screenshot below.

One way that Connect may have driven traffic to CNN is that the chat messages appeared within user profiles and on news feeds on Facebook, so friends would see that you were watching the inauguration and go chat with you on CNN. Of course, Facebook and CNN both advertised the service beforehand, so that certainly affected overall usage. We don’t have detailed numbers to help us sort out why CNN’s traffic was so much higher than rivals during the inauguration, but it could be an early indicator of where Connect is going.