Eh a lot of States are shaped by successive land aquisitions. They are territories then the state borders were defined upon statehood. These aquisitions by conquering or purchase happened over many decades. The national border of the time being adopted as a state border. This were often based on geographical details. After the Louisiana purchase there was a ton of land and it made sense to use a mixture of big squares and pre-existing territory borders. Though big landmarks like the Columbia/Mississippi rivers or mountain ranges play a role.

Though there’s lots of politics involved but there’s skates Wikipedia.