It's the time in which but it's the time in which long distance commerce began to take hold, because of transportation revolutions: canals, roads, railroads in particular.

它是一个时期,这是一个远距离商业开始产生影响的时代,主要原因便是运输方式的革新,运河,公路,特别是铁路

耶鲁公开课 - 美国内战与重建课程节选