Distribution of trees in the United States

Technically this shows "above-ground woody biomass," but in practical terms it is a map of tree density.

Over six years, researchers assembled the national forest map from space-based radar, satellite sensors, computer models, and a massive amount of ground-based data. It is possibly the highest resolution and most detailed view of forest structure and carbon storage ever assembled for any country.

Forests in the U.S. were mapped down to a scale of 30 meters, or roughly 10 computer display pixels for every hectare of land (4 pixels per acre). They divided the country into 66 mapping zones and ended up mapping 265 million segments of the American land surface...

Posted at Neatorama by Miss Cellania, who found it at NASA's Earth Observatory (their Image of the Day page is well worth a bookmark).

p.s. - The embedded image enlarges with a click, but I jpegged it to save on my allotted space at Blogspot.  For maximum detail, enlarge the original at NASA.