Acreage of Highways
Just how much area do USA highways take up?
A USA highway is typically 200 feet wide (including shoulder and righ-of-way) - 76 feet in minimum width with shoulder for 2-lane highway, plus whatever land is taken until land can be used for applications other than right-of-way. Thus, there are ~24 acres covered by US highways per mile or highway length.
For comparison, it would take 100x100 miles to power up all of the USA's electric needs.  This is about 7 million acres. Must says that the battery to store all of this would be 1 square mile.
Thus, just using highway right of ways would provide 1/7 of the USA's electricity!
- Roads are 4M miles. Only 1.2% is interstate highways.