I live in the Midwest and I've actually taken up to 2 hours to leave, so I have some experience here lol. When it takes that long to leave, it's because it's a huge family gathering of some kind. The most recent for me was a huge family wedding. It's kinda rude to just leave without making rounds to folks, so the time is spent tracking people down and talking to them for about 5 minutes before looking for the next person. Obviously you can't say goodbye to everyone, so I just say goodbye to everyone I'm close to before saying goodbye to the host