The Only Two-Sided State Flag

Oregon is the only state in the United States with a two-sided state flag. The front features the state seal with the words State of Oregon above it, while the back shows a gold beaver, the state animal, on a blue background. No other U.S. state flag has a different design on its reverse. The beaver was chosen because of the central role the fur trade played in Oregon's early settlement, as beaver pelts were the most valuable commodity driving exploration and commerce in the Pacific Northwest throughout the early 1800s.

Source: Wikipedia