I've always wanted to animate such a map, so that you could watch a family spread west and grow across N. America. After arriving in the US, my first generation walked across S.Carolina, the second across N. Carolina, Tennesse, to Kentucky, and the third across Kentucky, Illinois to western Missouri where they arrived in 1806. The fourth made it to California and back to Utah. I know that the 3rd generation pushed their belongings before them in carts (there were of course no roads). I find this migration hard to understand considering how nice the area of Inverness was where they all began.