To give some sense of scale: The US overlaid onto the moon

[Click here for hi-res]

via io9, which has more information and links to similar subjects:

The greatest distance between two points within the contiguous U.S. is 2,892 miles, stretching from Point Arena, CA to West Quoddy Head, ME*. The circumference of the Moon is 6,784. To help put the scale of each into perspective, redditor boredboarder8 decided to overlay one on top of the other, giving rise to the approximation you see above.