The United States obviously has a lot of straight-line borders you don't see in Europe. What I'd like to try is to get rid of them all by having the British re-organise the thirteen colonies into new polities with natural borders, and for that precedent to continue as they expand West after independence.
It also does not need to be the same number of states: in fact, it's better not to be. You get bonus points for having the new polities being based along cultural and economic splits.