How Much Gas to See the Country?

In the early years of the automobile in the United States there was a feeling of freedom and almost mystical liberty attached to owning one. The famous highways and the idea that Joe Typical was now empowered to see the entire country. The idea that now anybody could overcome the tyranny of distance. This ease of movement and shrinking of apparent distance depended not only on cheap automobiles but on cheap gasoline. So let us see how much gas it might take to see the country.

First we have to decide on what we mean by "See the Country". Let us consider taking a trip that passes through Washington DC and one city in each state. We will follow a path that visits each of these 49 cities exactly once, and we will go around in a loop, finishing where we started. There are very many possible such paths, even after we have picked our 49 cities. We will choose the shortest such path, so as to save on gas. Finding the sequence of cities to visit that gives the shortest road distance to travel is a hard problem, known in the technical literature as the Traveling Salesman Problem. In the case of our tour through a city from each of the 48 continental states plus Washington DC, a solution was worked out in the 1950s. You can read this paper by Dantzig, Fulkerson and Johnson which finds and proves the shortest road distance path. The picture above illustrates the cities and the shortest route. The paper lists the cities themselves.

The shortest tour around our 49 cities has a total length of 12,345 miles. So any road tour of the country that visits each of our continental state cities and Washington will put at least that much on your odometer. Visiting those 49 cities gives a pretty good claim that you have seen the whole country. Now how much gas will that take? It depends on the fuel economy of the vehicle you drive. We will use the highway mileage estimates because most of that driving will be at speed on interstates and freeways without stops and slowdowns due to traffic.

A 2010 Acura RL gets 22 miles per gallon on the highway according to the EPA. If we get to know the country in such an Acura, we will use 560 gallons or so of gas. Gas Buddy is showing a US national average fuel price of $2.635 per gallon today. Using that price, we would spend $1480 keeping the gas tank of our Acura topped up.

That is not cheap, and of course a national tour will have other costs (like food and lodging). However, considering that the US occupies a pretty big land area it is an amount of money remarkably within reach. Joe Typical can afford that much gas if he wants to. So even today the car still delivers on some of that century old mystique of mobility and motion.

By learning to save on gas and building highly fuel efficient cars we can make sure that even in a tomorrow featuring yet higher priced gasoline that mystique stays alive.

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