Jewish were the hardest to hid
C. Yellowstone is the most popular park in the summer, but it is the least popular in the autumn.
Before things like mountains were typically boundaries since they were a pain in the butt to cross. But with modern planes, and depending on the mountian, cars, mountains aren't as big a pain anymore. Deserts might have also been a boundary before. Today you turn on the AC and drive straight across it. At least for technologically advanced western countries, there really isn't any geographic feature we can't easily get around.