An 1880 Royal Commission on the state of New Zealand's railways felt that an east coast main line would be premature, but possibly necessary in the future.

Contrarily, regional actors in Canterbury, Marlborough, Nelson, and the West Coast argued passionately in favour of the proposals that best suited their interests.

Canterbury slowly progressed its "Great Northern Railway" and pursued an inland route from Waipara, reaching Waikari in 1882, Medbury in 1884, and Culverden in 1886.

This reached Scargill in 1902, Ethelton in 1905, Domett in 1907, Cheviot in 1910 (the station was in nearby Mina), and in 1912 the line crossed the Waiau River with a 706-metre-long (2,316 ft) bridge and was opened to Parnassus.

The 1920s saw little progress made on the Main North Line as various interest groups, governments, and expert reports contested to achieve their respective desired outcomes.

In the late 1920s, construction finally recommenced on the coastal line south of Wharanui, but this soon stopped again when the Great Depression's effects began to be severely felt.

Public pressure for a resumption of work was strong, and as the economy was starting to improve in 1936 the government issued orders for completion in four years.

In 1939, the line beyond Parnassus was opened to Hundalee, but the outbreak of World War II created more delays and the goal of completion in four years was not achieved.

[11] For a number of decades before the connection of the northern and southern ends, the Canterbury section was operated with its terminus in Culverden, even when the coastal route reached Parnassus.

In 1930, a Royal Commission on New Zealand's railways suggested all passenger services on the southern and northern sections be replaced by mixed trains, but this was not positively received by the public.

[14] The scenic value of the route, especially through the Kaikōura area, led to the creation of the tourist-focused Coastal Pacific, an express passenger train that ran between Christchurch and Picton in 5 hours and 20 minutes.

[14] The TranzCoastal was suspended as a result of the major Christchurch earthquake in February 2011 and did not resume until August that year, returning to the original Coastal Pacific name.

The line between Picton and Spring Creek yard remained open to allow rail wagon freight from the Interislander ferries to be transshipped to road and vice versa.

[16][17][18] In November 2018, Prime Minister Jacinda Ardern announced that KiwiRail is to get $40 million from the Provincial Growth Fund, to provide a year-round service by the Coastal Pacific and to upgrade the Kaikōura, Blenheim and Picton stations.

A 1994 attempt to regain Auckland-Christchurch freight, with a 24-hour journey, lasted only a couple of years and by 2012 rail's share of that traffic was 28%, road's 57% and ship's 15%.