How were the boundaries configured for each...

There’s enough here for several doctoral dissertations, but suffice it to say that, before Thomas Jefferson, state boundaries tended to follow natural separators such as rivers and mountain ridges, or historically accepted boundaries. Jefferson, however, successfully proposed that western states be divided into a tidy checkerboard pattern. As a result, every state west of the Mississippi has at least two straight, or mostly straight, sides, except Oregon, Minnesota, and Texas. This square-corner arrangement, however, doesn’t translate well on a spherical planet, and some of the lines have been adjusted accordingly. (Guest Expert Nancy Carter, Denver, Colorado)