First, his calculations comprise transportation between the primary markets of the Midwest and the secondary markets of the East and South (interregional) and transportation between cities and rural areas (intraregional).
首先他的计算包含了中西部的主要市场和东部和南部的次要市场之间的交通运输（跨区域），以及城市和农村地区（跨区域）之间的交通运输。