The first proposal for a line resembling the present day Main North Line was made in 1861. A proposal for a line linking Christchurch and Blenheim was put before the Marlborough Provincial Council in April 1861. Later that year, the national government passed the Picton Railway Act in October, approving a line from Picton to the Wairau River under the auspices of the Marlborough Provincial Council. However, the political authorisation did not translate into actual construction and no work on building the line was undertaken in the 1860s. In the 1870s the Canterbury Provincial Railways began to extend their broad gauge network north from Christchurch through Kaiapoi and Rangiora, reaching Amberley in 1876 and Waipara in 1880 - by this stage, the Canterbury network had been re-gauged to the national gauge of narrow gauge and acquired by the central government.