I then wondered what effect temperature may have had on ridership based on extreme heat here in Arizona.  Granted I was only able to use average monthly temperature and monthly ridership numbers instead of being able to plot ridership everyday by temperature.  I would like someone with that data to plot it though or post the daily ridership numbers so someone else can plot it.

Lastly I wanted to see what effect gasoline prices had on ridership.  I was only able to use average gas prices with month totals instead of average gas price by day and ridership by day.

All in all this data is probably useless for several reasons.  Gas prices jump dramatically during the summer almost directly at the same time temperatures rise here in Arizona.  Rising gas prices and temperatures happen at the same time students are out of school and snow birds are gone.  Would love to hear various theories and see more data.