Passenger transportation volume of railways tended to grow until 1955 to 1964; however, after 1965, many small-and-medium-sized private railways were discontinued because of change in population distribution (concentration of population in large cities) along with change in industrial structures in the high economic growth period, and reduction in transportation volume of small-and-medium-sized private railways in local areas due to the widespread use of private cars.
昭和30年代までは全体的に増加傾向にあったが、昭和40年代以降は、まず高度経済成長期の産業構造の変化にともなう人口分布の変化（大都市への集中）と、自家用自動車の普及により地方中小私鉄の輸送量減少が進み、多くの中小私鉄が廃線となった。