What are the only two U.S. states whose shapes are completely rectangular?

While many state lines follow the winding paths of rivers or the jagged peaks of mountain ranges, two states in the American West stand out for their simple, geometric precision. Their boundaries were not determined by natural landmarks but were instead drawn on a map using specific lines of latitude for their northern and southern borders, and lines of longitude for their eastern and western borders. This creates what appear to be two perfect rectangles stacked on top of each other.

This straightforward approach to border-making was a product of 19th-century westward expansion. As the United States organized vast, sparsely populated lands acquired through treaties and purchases, it was often simpler for cartographers and politicians to define new territories with a ruler than to survey complex natural features on the ground. Both Wyoming and Colorado were carved from larger territories in this manner, resulting in their famously boxy shapes.

Interestingly, neither state is a true mathematical rectangle. Because the Earth is a sphere, lines of longitude actually converge as they travel north toward the pole. This means that the northern border of both states is technically a few miles shorter than their southern border. As a result, their true shapes are trapezoids, though they remain the most famously rectangular-looking states in the union.