We are so close to the end of the series, damn it was a great ride

The series is about two kids being sent on a summer vacation, and therefore takes place over the course of just one summer. At this point they must be much closer to the end of summer than the beginning, because way too many events have already happened, and in the latest episode Mabel writes that they've already spent "a few months" in Gravity Falls. So it looks like in the end of this season the summer will end, and the twins will have to pack their things and take a bus back home to their parents.

Moreover, since the twins are 12 and their birthday is on the last day of summer, this is technically the last summer of their childhood. It seems like the last episode will be about them finally growing up – a fitting story for the series finale. So yes, in all likelihood we are very close to the end of the series.

But who knows? Perhaps the twins will convince their parents to allow them stay at Gravity Falls and go to school there, or will return there next summer as teens…