In the sections called mini-Shinkansen lines (the section between Fukushima and Shinjo of the Yamagata Shinkansen line and that between Morioka and Akita in the Akita Shinkansen line), the gauge of the regular railway lines has been changed to the standard one to enable through operation as limited express through Shinkansen.
ミニ新幹線と呼ばれる区間（山形新幹線の福島-新庄間、秋田新幹線の盛岡-秋田間）は、在来線の線路を標準軌に改軌改良し、新幹線直行特急として直通乗り入れを行っている。