2012 Chevrolt Volt Gas Station Advert

2012 Chevrolt Volt Gas Station Advert

Electric cars achieved another milestone recently: Plug-in vehicles on American roads now outnumber the gas stations they whiz past on the roadside.

We estimate the watershed (oil-shed?) event took place in early July--though there are some asterisks, as we'll discuss below.

As early as next year, electric-car sales in the United States each year could top the national gas station count.

That would make it possible for electric-car fans to create a sort of "Gas Freedom Day," much as some Americans today celebrate the annual "Tax Freedom Day."

Plug-ins lead gas stations, 120,000 to 119,000*

According to the most recent U.S. Census data, there were 118,756 gas stations in the United States in 2007. (Census 2012 data isn't yet available, but there's been a steady decline in numbers over the years.)

2012 Toyota Prius Plug-In Hybrid - production model

2012 Toyota Prius Plug-In Hybrid - production model

Our best estimate is that there have been about 120,000 cumulative plug-in electric vehicle sales in the U.S. thus far, comprising roughly:

As for that asterisk: The National Petroleum News claims there are 157,393 gas stations, a difference of fully 40,000 from the Census number.

That statistic comes from the NPN's 2011 MarketFacts report, which tracks all manner of industry data, from state-by-state pump prices to pork-rind sales at gas-station convenience stores (they're a quarter-billion-dollar business, it turns out).

Census vs. NPN

Part of the difference comes from the fact that the U.S. Census derives its numbers from NAICS codes - a system which classifies businesses by their primary endeavor.

The roughly 4,000 gas stations run by America's big-box stores don't register in the Census lists, and 10,000 automated gas stations (mainly stations for truckers that require a special card to unlock pumps) are categorized separately.

Smaller retailers who don't break out gasoline sales from general revenue may also get overlooked.

Gas prices, San Francisco, CA

Gas prices, San Francisco, CA

That said, being government data, the Census is publicly and freely available, and reasonably transparent. Unfortunately, it's only updated every five years, so the numbers we used are slightly out of date.

While the NPN data is updated every year, being a private organization, they might be reluctant to divulge the particulars of their data collection methods.

They also put some of their gas-station data behind a paywall, as they have for their state-by-state statistics for 2007.

Choose the data, name the date!

Regardless of which station total you use, either we've already passed it or we're well on the way--and will do so before the end of this year.

Before we launch an annual celebration of the day that plug-in electric vehicles on the roads outnumbered gasoline outlets, though, we need to make some decisions.

First, would you prefer us to use the numbers from the U.S. Census, or those of the National Petroleum News?

Second, we have to name the day. We came up with "Oil Revoir Day," and also "Passing Gas Day"--do you have a preference? Or is there another name entirely you'd prefer?

On both questions, give us your thoughts in the Comments below (or via Twitter at @GreenCarReports)

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