英语语法分析

During periods when commodity prices were high, the rate of westward migration increased spectacularly.

在商品价格较高的时期，西迁的速度大幅增长。

"Old America seemed to be breaking up and moving westward," observed an English visitor in 1817, during the first great wave of migration.

1817年，在第一次移民大潮中，一位英国游客观察到：“古老的美洲似乎正在分裂并向西移动。”

Therefore, these social traits helped to produce the nomadic and daring settlers who kept pushing westward beyond the fringes of settlement.

因此，这些社会特征有利于造就流浪在外并且大胆的移民，这些移民会一直向西迁移到比定居点更遥远的地方。