"Over the river and through the woods, to grandmother's house we go" ... and how much should we expect to pay for gasoline during the trip? Read this blog to find out!

I recently wrote a blog post about some of the factors that impact the price of gasoline. The blog had some interesting information, but when it comes down to it what we really want to know is how much will we be paying for our next tank of gas!

You've probably got your favorite low-price gas station in your local city, but did you know that the prices vary widely from state to state? According to AAA, the state averages for regular grade gasoline range from \$2.25 to \$3.70 per gallon today! Therefore, if you're going to be driving on a long trip, you might be able to save some money by planning your route, or the timing of your fill-ups, so you're buying gas in one of the lower-priced states.

To analyze & visualize the data in SAS, I wrote a little program that reads in the HTML code of the AAA Web page, and parses out the state names and gasoline prices, and then plots the prices on a map, color coded by quintiles (each 1/5 of the states are a different color, based on their gasoline price):

The above map is great for quickly determining which states have higher and lower gasoline prices. But what about the 'impact' of those prices? I thought it would also be interesting to know how many people the high & low prices are affecting. For example, although Wyoming is a fairly large state geographically (and therefore has a lot of 'red' in the map above), the population is low, and therefore the high gasoline price in Wyoming doesn't affect many people.

In order to visually 'weight' the map by population, I plotted the data using a rectangular tree map, where the size of each rectangle represents the number of people in each state. Now it's easier to see, for example, that Texas has a low gasoline price (bright green), and also has a large population (large rectangle size).

Now that you've seen the data, what state do you plan to fill up in, while traveling over the holidays?

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The Graph Guy!

Robert has worked at SAS for over a quarter century, and his specialty is customizing graphs and maps - adding those little extra touches that help them answer your questions at a glance. His educational background is in Computer Science, and he holds a BS, MS, and PhD from NC State University.

1. Chris Hemedinger on

I'll be driving through 3 pink/purple states over the holidays -- I'm probably going to have to fuel up in at least one of them, unfortunately.

• Robert Allison on

Well, you might not be getting the cheapest gas in the US ... but the price might drop another 10 or 20 cents in the next week or two, so at least there's that! :)

2. You may need to revise this map. I just heard on the news this morning that there are 14 states where gas is less than \$2.00. ;-)

• I think those were states "where gas can be found for less than \$2" ... but their state average still isn't less than \$2 -- At least, not yet! :)

3. Michae A. Raithel on

Bob,
Another great article and group of graphs! Never thought I would be living in a pink state:-) !