Its not like there were tons of ads or the like pushing the movie. Actually, the only true publicity I saw, and only trailer I saw, was off of the web. It was all because of the build up. The Star Wars series has become an instant cult classic. It proves one thing.
Teaser campaigns work.
Not only that, but people have a herd mentality. Since everyone else was going, and they were going to be talking about it at work, we just had to go. Not only that, but the fact that the tickets were limited, made people want to go even more. I saw an ISP stop taking residential customers, and focus on business customers. They would only replace those residential customers who left on a 1 to 1 ratio.