I'd like to find a site that gathers all this stuff together. There's a lot of information out there, but you have go hunting for it.
This report, for example, explains that driving to the supermarket adds far more to the cost of getting your groceries than does importing them by ship in the first place, and that indeed importing fresh produce by
air can sometimes be more energy-efficient than producing it locally.
There are a number of studies that have shown that buying locally-produced food from farmers' markets is also
less energy efficient than getting it from your supermarket.
City apartment buildings are
more energy-efficient, more water-efficient, and, of course, vastly more land-efficient than individual houses.
So it goes.
And, of course, the proportion of people employed in agriculture in the US has declined from over 40% to around 2% in just a few decades. Where are you going to put the 98% of people who aren't involved in farming? You don't want them cluttering up good farmland with new houses and roads. No, you want them in a densely-populated city that occupies as little land as possible.