and to its greatest extent of 4,755 route miles (7652 km) in 1939. The result was that by the beginning of the 20th century, no Victorian (apart from those in the mountain regions) was more than 25 miles (42 km) from a railway line. The period from the end of the 1930s saw a slow decline in route mileage as unprofitable branches were closed. Conversion of the Melbourne suburban system to electric operation commenced in 1919 and was completed by 1930, creating what was claimed at the time to be the world's largest electric suburban rail system. 1937 saw the introduction of the streamlined Spirit of Progress passenger train, with air conditioning and all steel carriage construction. Diesel power was introduced in 1951 with ten F-class diesel-electric shunting locomotives, followed by B-class mainline diesel-electric locomotives in 1952/53. A standard gauge line connecting to the New South Wales system was constructed in 1961 allowing through trains to operate between Melbourne and Sydney, Australia's two largest cities, for the first time. The last steam locomotive was withdrawn in 1972. Demise In May 1973, the Railways (Amendment) Act 1972 passed the management of the Railways from the Victorian Railways Commissioners to a Victorian Railways Board. In 1974, the Victorian Railways was rebranded as VicRail, but the royal blue and gold livery used on rolling stock was retained until 1981. In 1983, VicRail was divided into two—the State Transport Authority taking responsibility for the provision of country rail and road, passenger and freight services, and the Metropolitan Transit Authority taking over suburban passenger operations. The State Transport Authority traded under the V/Line name, while the Metropolitan Transit Authority used that name until the Public Transport Corporation ("The Met") was formed in 1989. Between 1996 and 1999, V/Line and The Met were privatised. V/Line Passenger was franchised to National Express, returning to government ownership in 2002. The V/Line Freight division was sold to Freight Victoria and is now owned by Pacific National. The infrastructure is now managed by VicTrack with the interstate rail freight infrastructure leased to the Australian Rail Track Corporation. Metro Trains Melbourne now operates the suburban railway network. Management When first formed in 1857, the management of the Railways Department was initially vested in the President of the Board of Land and Works, this situation remaining until 1884. With the passing of the Victorian Railways Commissioners Act 1883, a board of four