Electric trains have begun operating between Chesterfield and Newton Le Willows, marking the completion of the first phase in Network Rail's programme.
Overall, the £400 million scheme aims to electrify 350 km of track across the north of England by December 2018. So far, the organisation reports progress is both on time and under budget.
The stretch of track between Willows and Castlefield Junction, close to Manchester Piccadilly, is also part of the world's oldest public railway.
Network Rail's route managing director Dyan Crowther said: "This is the first railway line to be electrified in England in over a decade. We have delivered this complex project, using modern standards and state-of-the-art technology, in four years from inception."
She further stated the programme would be finished in the north-west by 2016.
The second phase, out of a total of five, aims to upgrade areas between Liverpool and Newton Le Willows, between Huyton and Wigan, and from Ordsall Lane to Manchester Victoria station by December next year.