Interesting to note that counting rides by a bounded geographic area is going to miss a lot, as the caltrain data doesn't seem to be represented in the santa clara data.

Also, the Austin data doesn't take into account that the city regularly expands its geographic boundaries (typically east and west) which may artificially make it seem as if it is increasing riders when it is simply absorbing them.

In 15 years, how much has road usage grown and how much has population grown? Just a 2x increase seems like a relative decline.