This isn't photoshopped! You can see it for yourself on Google Maps. Redditor BobinMinn uncovered this treasure. According to another redditor, satellite images indicate that this little Minnesota has been around since at least 1991.
What's going on here? 2 commenters at this CityPages post explain. This forest is on state-managed land. The state government hires foresters to cut down sections for ecological reasons:
I was a forester in northern Minnesota for some time and I can tell you this. This is state forest land, managed by DNR Division of Forestry. The state employs foresters to design timber harvests to meet many objectives including ecological and economic ones. The forester who designed this timber sale is a veteran at his craft and created this boundary line without the use of gps, but with map and compass instead. The forest type is jack pine, which is an early successional species that colonizes sites after a major disturbance and needs full sun to thrive. This species occurs in fire dependent forests. Modern timber sales mimic the effect of fire in these landscapes. As such this large opening was created to encourage it's regeneration. Loggers are contractors of the landowners/ land managers, and as such do not have discretion as to the layout of the harvest or other design features. They perform the contract. This forester must have an artistic side.