The agreement between France and Italy on building a tunnel was signed in 1949. Two operating companies were founded, each responsible for one half of the tunnel: the French Autoroutes et tunnel du Mont-Blanc (ATMB), founded on 30 April 1958, and the Italian Società italiana per azioni per il Traforo del Monte Bianco (SITMB), founded on 1 September 1957. Drilling began in 1959 and was completed in 1962; the tunnel was opened to traffic on 19 July 1965.