Challenge Revisited: Pump Price

Back in 2005, I first posted the Pump Price Challenge.  I had to update it a few times due to inflation and additional sites that people were finding.

Now in 2011, the question could be: How much did people pay for gas at the pump in 1920? How much would that be in 2011 dollars?

The value of the dollar keeps changing due to global economics and inflation so this is definitely a moving target.

The challenge is to find an authoritative site (think: who is an authority on inflation?) so you can convert the price of a gallon of gas in 1920 into the most current dollar information.

This isn't a particularly hard search, but it requires finding a site that is regularly refreshed.

Challenge One: Find an authoritative site where information on inflation is regularly updated.
Challenge Two: use that to determine what a gallon of gas in 1920 costs today.
Challenge Three: use the most current information to determine what a gallon of gas purchased in 1981 would cost in 2011 dollars. (Yikes!)

I found a good site, but there could be more. I'll consider other alternatives for redesigning the pump challenge.