Well, all Western states of the US have funny shapes, as if they had been traced with a ruler and distributed thus.
If you locate the state of Oklahoma on the map (right above Texas), you will notice the funny rectangle on its Western part. This is the Oklahoma panhandle (because it reminds you of the handle of a pan).
Why does Oklahoma have this panhandle? How was it formed?
Its story is quite interesting.
We have to go back in time to the 19th century to a nation in formation, and having issues of territory and of slavery.
It all started with the 1820 Missouri Compromise Line, which prohibited slavery north of the parallel 36°30′ North, except in Missouri.
That line compromised the northest part of the territory of Texas, which was left above the line.
Texas, which by then was not yet a state nor a republic and was controlled by Mexico, preferred to keep slavery so it gave up the strip of north territory. In 1854, the Kansas southern boundary was moved northward to parallel 37° North. Thus, a strip of land was left between 36° 30′ N and 37° N, which then became Public Land Strip or No Man’s Land for a long time.
In 1890, an act made the Strip part of Oklahoma Territory, which later became the State of Oklahoma.