How gasoline use varies among metropolitan areas

Back in March, I wrote about economists Matthew Kahn and Ed Glaeser's work comparing carbon emissions among metropolitan areas.

Among other things, they estimated how carbon emissions from driving vary across metropolitan areas.  The variation in gasoline use is just as interesting, though.  Kahn and Glaeser did not explicitly calculate this, but I did the simple arithmetic to convert their estimates of carbon emissions to estimates of gasoline use.  

In my last post, I was working from their relatively short, "popular" article, which provided data for just ten MSAs.  I have now put my hands on their full paper[1] (gated, unfortunately), which provides estimates for 66 MSAs.  I've again converted their estimates of carbon emissions to estimates of gasoline use.   

What's neat about Kahn and Glaeser's approach is that they've tried to make an apples-to-apples comparison.  Simply calculating gasoline use per household is misleading because some metropolitan areas are wealthier than others, and wealthier people tend to use more gasoline, all else being equal.  Also, households tend to use more gasoline as they increase in size; thus, a metropolitan area with lots of large households will use more gasoline than a metropolitan area with lots of one-person households.  Kahn and Glaeser have tried to fix this problem by estimating how household income and size affect gasoline consumption.  They then estimated gasoline consumption for a household with 2.62 members earning $62,500/year.

They also estimated the impact on gasoline consumption of MSA density, census tract density, and distance from the Central Business District.   And they found that gasoline use varies across regions; Southerners simply drive more than people out West, for example, even after controlling for things like density.  Using these estimates, they predicted, for each MSA, the "standard" household's gasoline consumption. 

The results are below.  Just for fun, I compared gasoline consumption in Austin to gasoline consumption in other MSAs.  Austin does not fare well under their methodology, mainly because it is not very dense and a large percentage of the population lives relatively far from the CBD. 

 

(Here's the spreadsheet on Google Docs) 

Note that this allows a rough estimate of the relative amount of pain inflicted by gas price increases.  For example, using their estimates, a $1 increase in the price of gasoline costs the standard household in Houston $60 more per year than the standard household in Portland.  (Remember that these are aggregate MSA estimates; they don't permit comparisons between the residents of Houston's suburbs and the residents of central Portland.  They also have not explicitly factored in the effect of transit on gasoline consumption, although that will be captured to some extent by their adjustment for density.)      

[1] Kahn & Glaeser, The Greenness of Cities: Carbon Dioxide Emissions and Urban Development August 2008 NBER Working Paper #14238 www.nber.org.

Comments

[natrius]

I wonder how politically persuasive the environmental angle to easing the overly restrictive zoning in central Austin would be. I'm guessing not at all, but does anyone even try? I guess Cid Galindo used it somewhat for greenfield density, and even that was a pretty hard sell. Democracy depresses me.

[AC]

My read is that neighborhood groups use environmental arguments when they support their goals and ignore them when they do not. Some council members, at least, have at least cited environmental concerns in approving infill density.

[M1EK]

Another good launching pad for discussion. By the way, http://austincontrarian.com/ should probably redirect here.

I'd point out that $62,500 in Houston is completely different from $62,500 in New York or San Jose. Of course, the standard adjustments for cost-of-living are awful too, as they tend to force everybody into the same style of housing (costing out a single-family house in Honolulu even though the majority of households live in multi-family dwellings, for instance).

[AC]

Thanks for the reminder on the link -- I've just got fiddle around with some code on Typepad.

[Jude Galligan]

Thanks, Chris. It's interesting how the numbers show Austin drivers are bigger consumers of gasoline compared to Houston or Dallas. Recently I've been focused on the damage that mandatory parking requirements cause. Tax gasoline, use the funds as capital for mass transit, restrict parking. That's the magic gumbo to get people out of their cars. On a recent trip to Vancouver, one of their [very respected] council members said "Show me your parking ordinance, and I'll show you what your city looks like." -Jude

[bittergradstudent]

How are they defining the metropolitan area? Are they just defining it according to the central county, and not worrying about weird distorting effects?

I ask this because:

1)these data resolve the Boston and Providence metro areas
2)I refuse to believe that Austinites drive less than St. Louisians, unless Austinites are somehow getting a penalty for having higher land values. I've lived in both places, and it's possible to not own a car here, while it's very difficult to live without a car there, due to a larger physical size of the city, a less extensive transit system (though at least their light rail does trace two major transit corridors), and having three major rivers to cross.

Also, LA being where it is strikes me as weird, to say the least, considering the constant complaining about drive/commute times from everyone I've ever met that has lived in LA. Once again, it's probably an effect of weighting for housing values. Still, a lot of that chart seems somewhat counterintuitive.

[AC]

Jude, I'm not high on maximum parking restrictions (although minimum parking requirements are even worse). Lenders won't lend money without "enough" parking, unless they can be convinced that there's enough mass transit to serve the building. If Austin develops a decent mass transit system, then developers will gladly reduce parking (if the city lets them) and the lenders might go along with it.

Downtown Austin is chock full of parking garages already. I haven't done a survey to see if they're full during the day. I imagine there is unused capacity here and there that could be put to better use. There's certainly enough parking capacity to serve nighttime and weekend visitors.

The trick is unlocking the parking capacity we've got. As M1EK's pointed out before, it's a pain in the ass to open up a private garage to the public. Some buildings do it (mine does) but there has to be a lot of parking to make it worthwhile. If I were the city, I'd form a PUD or otherwise encourage downtown businesses to put money into a pot which would then be used to incentivize garage owners to open their excess parking to the public.

[AC]

BGS, Kahn & Glaeser use 2000 Census definitions of MSAs. "The general concept of a metropolitan statistical area is that of a core area containing a substantial population nucleus, together with adjacent communities having a high degree of economic and social integration with that core." (See http://www.census.gov/population/www/metroareas/aboutmetro.html for more than you ever wanted to know.) They are county-centric.

It's quite possible that car-use in a specific city deviates from their prediction. Their prediction is based on a few coarse factors -- MSA density, census tract density, distance from CBD, geographic region -- which they say collectively explain about 30% of the variation in individual gas consumption. (Obviously, there's a lot of variation among households just due to idiosyncratic factors.)

So it is quite possible that their estimate is off for one city or another, although any such city will be an outlier.