City Slicker vs. Country Bumpkin: Who Has a Smaller Carbon Footprint?

Remember I said that I thought studies showed the greenhouse gas emissions per capita of people in cities were less than those of people in the country? But I couldn't remember the study.
Here is one, reported in LiveScience, that was done in 2009 and backed up by 20 or 30 follow-up studies, so says the article.
In short, and on average, city dwellers do indeed emit fewer carbon dioxide emissions per person than country folk.