The first Metro network was completed with the public opening of Line 4 (Yellow Line) on April 28, 1967. The cities of Montreal, Longueuil and Westmount had assumed the entire cost of construction and equipment of $213.7 million ($1.6 billion in 2016). Montreal became the seventh city in North America to operate a subway. The 1960s being very optimistic years, Metro planning did not escape the general exuberance of the time, and a 1967 study ″Horizon 2000″ imagined a network of of tunnels for the year 2000.