The history of rail transport in Chile has gone through several periods of boom and bust. It began in 1840, with the construction of the first branch in the north (from Copiapo Caldera). Further construction proceeded apace linking cities from Pisagua all the way to Puerto Montt. In addition, there was a network on the big island of Chiloe, and a host of now completely abandoned branches. Four cross border lines were also built: At its peak in 1913, the national rail system had 7,658 km of track. It carried about 21 million passengers in 1946 and about 27 million in 1973.