On Christmas Eve and Christmas Day, Facebook was for the first time ever the most visited site in the United States. Today’s stats aren’t too surprising. The web measurement firm, Hitwise, reported a massive Christmas spike in Facebook traffic a year ago, as well, although Facebook was not the number one site then. However, it has grown from 42 million monthly active US users to 100 million in the past year, according to the numbers the company reports in its advertising tools. And earlier this month, Hitwise also reported that Facebook had become the number one search term in the US in the past year.

And while Facebook has grown from less than 150 million to 350 million monthly active users in the past year worldwide; in the UK, Google is still number one.

Clearly, a broad swath of people are checking Facebook during Christmas. Given the rapid growth the service has seen among all demographics in the past year, Facebook is becoming more than ever a key way for friends and family to stay in touch with each other if they could not be together in person.

Another quite interesting piece of data about that: many popular social games and other applications actually saw their numbers drop on Christmas. It may be that users preferred to use photo albums, status updates, notes and other utility-based features for sharing with each other, rather than playing games together.