Historians such as Frederick Jackson Turner have long argued that the expansion and exploration into the west has nurtured a more independent spirit, as each pioneer battled the wilderness and each other for their own survival.

弗雷德里克·杰克逊·特纳 (Frederick Jackson Turner) 等历史学家长期以来一直认为，向西部的扩张和探索培养了一种更加独立的精神，因为每个先驱者都为自己的生存而与荒野和彼此作战。