What if we paved over the whole state of Wisconsin?
Actually, we already have. According to recent Federal Highway Administration figures, the United States has close to 240 million motor vehicles -- almost 40 million more cars than there are licensed drivers -- and just under 4 million miles of paved roads for them to run on. All told, some 61,000 square miles of the United States -- an area just a little smaller than the Beaver State -- is solidly paved over, either with roads or with parking. And of course, there's always more pavement on the way.