[6] Rail transport played an important role in the opening up and development of the hinterland outside of New Zealand's predominantly dispersed and coastal settlements.

From the 1870s, the focus shifted to building a nationwide network linking major centres, especially during the Vogel Era of railway construction following the abolition of the provinces.

[14] In 1870, James Macandrew MHR called for another select committee to investigate the need for a law to require one uniform railway gauge for the entire colony.

[14] Information from Featherston and Dillon Bell reached Wellington in August 1870, and the second select committee to investigate whether a law was required for gauge uniformity met from that month.

[14][16] Sections of the Canterbury railway network were converted to dual-gauge, including Rakaia to Lyttelton, with new branch lines built to narrow gauge.

[17] From 1870, the central government of Sir Julius Vogel proposed infrastructure including a national railway network to be funded by overseas loans of £10 million, under the guise of the "Great Public Works Policy".

[22] Usually built with light tracks and light-weight rolling stock, bush tramways were usually connected to the national railway network and were often moved as the forest was cleared.

One exception to this rule was the Ohai Railway Board in Southland, which was owned by the State Mines department and a local county council until its dissolution in 1990.

[25] The networks of the North and South Islands were independent of one another until the introduction of the inter-island roll-on roll-off rail ferry service in 1962 by the Railways Department, now branded The Interislander.

The company was sold for $328.3 million[29] to a consortium led by New Zealand merchant bank Fay Richwhite and US regional railroad Wisconsin Central Ltd.

The Midland Line for example, which mostly carries coal from the West Coast to Lyttelton, was assessed to be in a safe but poor state by the LTSA government safety body in 2003, and has needed major repairs.

Cited reasons included a "level playing field" for freight movements on road and rail, and ensuring access to the tracks for all interested parties.

[32] Toll Holdings of Australia made a successful takeover bid for Tranz Rail, subject to an agreement to sell back the infrastructure to the government for $1.

In exchange, Toll was granted exclusive use of the rail network subject to minimum freight and passenger volumes, payment of track access charges and its own investment in new rolling stock.

The government committed $200 million of taxpayer funding for deferred maintenance and capital improvements via a new subsidiary of the New Zealand Railways Corporation, ONTRACK.

[37] Instead of concluding a final track access agreement with Toll, in 2008 the government purchased the rail and ferry assets for $690 million, effective 1 July 2008.

Ownership of the national rail network is vested in KiwiRail Holdings Limited, with land owned by the New Zealand Railways Corporation.

Advocacy group Greater Auckland proposed the Regional Rapid Rail initiative in 2017, including tilt trains with a maximum speed of 160 km/h.

In December 2018, the Government of New Zealand committed funding to reintroducing a five-year trial rail service, named Te Huia, between Papakura in southern Auckland to Hamilton, starting in 2020.

[47] As a result of the COVID-19 pandemic in New Zealand, the Te Huia service had been delayed commencing operations to sometime after 3 August 2020, changed from its initial announced opening date of March 2020.

[53] In recent years, the amount of freight moved by rail has increased substantially and has started to gain market share in non-bulk areas as well.

[59] On April 12, 2022, KiwiRail announced the return of the Northern Explorer and Coastal Pacific services in September, alongside new multi day excursion trains at a later date.

In both cities, the respective local governments own the suburban passenger rolling stock and contract the operation of services to a third-party, in both cases Transdev.

Wellington's suburban rolling stock consists of electric multiple units, with diesel locomotive-hauled carriage trains used on the Wairarapa service.

Trains ran the 12 miles (19 km) between Napier and Hastings but some were replaced by a New Zealand Railways Road Services bus in 1926, and soon they ceased altogether.

[69] Worker's concession tickets had been introduced in 1897, initially for the Wellington-Hutt service, and extended next year to Auckland, Christchurch and Dunedin (and then between Westport and Waimangaroa).

[75] Premier Richard Seddon and the Liberal Government were keen to place secondary education "within the reach of the poorest man in the Colony" with an extension of the free passes in 1898 and 1909.

[81] Difficult terrain meant that some lines took years to complete, and has necessitated a number of complicated engineering feats, notably the Raurimu Spiral and Rimutaka Incline (the latter no longer in use).

[94] Due to a decline in rail freight volumes following land transport deregulation in 1983, and the introduction of electrification on the North Island Main Trunk, no new mainline diesel locomotives were introduced in the 1990s.

[104] Modern signalling, train detection and communications systems, as well as an overall decline in rail passenger traffic, has greatly decreased the number of fatal accidents occurring on New Zealand's railway network.