That's a very good observation. I grew up on the line (in Topeka). I believe it is roughly where Western expansion had reached at the time the transcontinenta

That's a very good observation. I grew up on the line (in Topeka). I believe it is roughly where Western expansion had reached at the time the transcontinental railroad was finished. I don't know if correlation equals causation there. It's also a line where water starts to be less available in Kansas and areas south.