During that same period, the first settlers began to move westward across the United States; this trend increased dramatically after the discovery of gold in California in 1849.

同一时期，第一批拓荒者开始横越美国向西探险了；在1849年加州发现金矿之后，这种趋势极速加快。

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During that same period, the first settlers began to move westward across the United States; this trend increased dramatically after the discovery of gold in California in 1849.

同一时期，第一批拓荒者开始横越美国向西探险了；在1849年加州发现金矿之后，这种趋势极速加快。

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