 Various outlying towns and villages were incorporated into the growing city of Aomori and with the absorption of the village of Nonai in 1962, Aomori became the largest city in the prefecture.In March 1985, after 23 years of labor and a financial investment of 700 billion yen, the Seikan Tunnel finally linked the islands of Honshū and Hokkaidō, thereby becoming the longest tunnel of its kind in the world.Almost exactly three years later, on March 13, railroad service was inaugurated on the Tsugaru Kaikyo Line.