On December 31, 1974, electric trains began to operate along the entire length of the Tarnowskie Góry - Kalety - Kluczbork - Ostrów Wlkp. - Jarocin - Poznań route (203 km). On the section Kluczbork - Ostrów Wlkp. Electric traction started earlier, i.e. on September 7, 1973. The electrification of the above-mentioned line created a second electric connection between Silesia and Poznań, and soon electric traction was introduced for further elements of port routes: Poznań - Inowrocław (101 km ) on December 14, 1976, and Jarocin - Gniezno (65 km)
