Jim of blogs for industry brings some much-needed data to the discussion of ag product transportation. After crunching some numbers from the Energy Information Administration (EIA), he concludes that:
[Commercial transportation adds up] to about 14% of total US energy consumption...which means that transportation of Ag products at "more than 20%" would be on the order of 3-4% [of total consumption.]
His estimates are probably good, and generally jive with other statistics provided by the EIA regarding petrol consumption. It is useful to keep in mind that the numbers he uses do not consider import of foreign products (and during the winter months, many fresh fruits and vegetables do come from South American sources). Huski may be correct in pointing out that eating only local foods makes an impact of questionable magnitude on the current energy market. But for many, the ethics of being earth-friendly are completely separable from economics. An article in today's San Francisco Chronicle illustrates that considering energy when choosing everyday foods is a growing habit for many people (†).
A decision clearly more important than food is in choosing good locations for cities before they are built. This may end up being a critical investment we can make in our nation's future; due to their scale and lack of density, our current urban models are overly dependent on abundant sources of energy for transportation. There are no guarantees that said energy will be around just two generations from now (‡).
The EIA says that the United States uses oil for transportation disproportionaly from the rest of the world. Mind you, this is not in a per capita sense (although I bet that's true too), but in a usage distribution sense. From the EIA:
In the United States, in contrast to other regions of the world, about 2/3 of all oil use is for transportation [...] (in most of the rest of the world, oil is more commonly used for space heating and power generation than for transportation.)
Why is this so? In part, because the United States is one of the only industrialized countries that has a high level of commercial activity even in the most inhospitable regions of its interior. North America contains regions of vastly differing climates, and time after time, we have chosen to plunk down entire communities where the local environments do not support agriculture (a.k.a. "life"). Life in a desert city, for example, would be impossible without access to cheap, abundant transportation. The "flourishing communities in the desert" require daily import of food for each of its citizens, a feat only an industrialized country could pull off, and one that is, if not unsustainable, then just plain dumb. I mean, seriously, why do people want to live in places like this? (Viewed along a different axis, the treeless suburban houses remind you an awful lot of the old Soviet-style apartment buildings...)
Why do people live there? I can only guess that it's the access to cheap housing. If true, this would suggest that we'll continue building "out" until we run out of fuel, literally. It's not apparent to me that there's a clear solution... but to be perfectly honest, Jim succeeded making me question whether or not there's a clear and present problem. I do know that I don't like the current method of urban outgrowth—it seems rediculous to plan urban, suburban and ex-urban communities the way we do now (which is to let the housing builders raze the local flora, construct entire residential zones consisting of identical houses in rows, then move on without planting more than 0.3 trees per hectare).
But this, I know, is an unpopular idea. Nobody wants the state dictating where to build housing (I certainly don't). I think the only way to fix this problem is to change the culture so that people would want live close to farms, close to clean water and close to public transportation. This is already happening in California, and as much as I would hate to admit it, the local/organic foods movement can take some credit for that. It remains to be seen if this attitude will be adopted elsewhere...
(†) See also: this article at infosthetics. Excerpt: 'OilStandard' illustrates a potential future when oil will replace gold as the standard by which we trade all other goods & currencies (thanks to Nick for the link).
(‡) For the record, I am certainly not proposing any Malthusian catastrophe. It's just that we may make life easier for future generations if we build cities in a way that has worked for thousands of years (i.e. densely, and close to water and agriculture), rather than the way we started just sixty years ago.
In the book and in public talks, Pollan basically suggests that Whole Foods, while an overall improvement on the supermarket experience, sometimes "pretties up" the image of organics without really staying true to what organic foods are all about. In a nutshell, Pollan contended that Whole Foods sells foods that meet the bare minimum standard for organics and yet aren't really what people would think about as organic. As an example, he cited a story in 
In particular, 
