The Far North Line was built in several stages through sparsely populated and undulating terrain within the Highland area of Scotland. Extending to , it runs north from Inverness to Wick and Thurso in Caithness, and currently carries a regular passenger train service.

It was completed in 1874, running round the western margin of the firths north of Inverness and then keeping to the coast as far as Helmsdale. From that point it turns inland through Forsinard, returning to the far north-east coast at Wick and Thurso.

Some intermediate stations were closed in 1960 but despite the construction of major road bridges across the firths significantly shortening the route by road, the line has seen some revival at the southern end due to housing development, and it has a secure future. The original through route of 1874 remains in use.

Inverness to Dingwall

The first railway reached Inverness in 1855, when the Inverness and Nairn Railway opened its line between Inverness and Nairn. In 1858 Aberdeen was reached, and connected with the developing Scottish railway network. Inverness was linked in to that network, although for the time being by a very roundabout route.H A Vallance, C R Clinker, Anthony J Lambert, The Highland Railway, David and Charles, Newton Abbot, 1985,

Soon after the opening of the Nairn line, thought was given to how the areas further north might be connected. The geography was not conducive to easy railway building, as the River Ness, the Caledonian Canal, the Beauly Firth and the River Conon lay in the way of northerly progress. Moreover, most of the population lay on the east coast, demanding that any railway attempt that side of the country. Shipping connections to piers and onward transport by connecting railway were considered. The Edinburgh and Northern Railway connected Edinburgh and Dundee and had two ferry crossings in that route, showing that such an arrangement could be commercially successful.

Such ideas came to nothing, but in 1859 Sir Alexander Matheson of Ardross promoted a railway that would run directly from Inverness to Invergordon. Matheson's tireless work resulted in the Inverness and Ross-shire Railway receiving its authorising act of Parliament, the Inverness and Ross-shire Railway Act 1860 (23 & 24 Vict. c. cxxxi), on 3 July 1860; the capital was to be £21,500, and the Inverness and Nairn Railway and the Inverness and Aberdeen Junction Railway were authorised to subscribe £10,000 and £15,000 respectively.David Ross, The Highland Railway, Tempus Publishing Limited, Stroud, 2005, The railway was to be in length. The construction was pushed forward energetically, with the bridges over the main waterways being quickly completed; the bridge over the Caledonian Canal was a swing bridge with a opening span; swing bridges were to be provided if required by the authorities over the River Ness and the Dingwall Canal; in the latter case a cash payment and free improvements to a small harbour bought off the requirement. The Beauly River was crossed by a timber bridge at this early stage.

There only remained the easier section north of Dingwall, and opening was anticipated for 1 April 1862, but unforeseen delays resulted in a later opening. Col. Yolland of the Board of Trade inspected the line between Inverness and Dingwall and passed it as fit for passenger operation on 10 June 1862. A wire was sent announcing that the line would open the following day, and a special train was run conveying the senior station staff to their posts in readiness.

The Inverness station had been built as a terminus for trains arriving from the east, and the frontage faced directly on to Academy Street, making it impossible to convert the station to a through configuration. The Inverness and Ross-shire Railway approached from the west, and curved in to the alignment of the existing station on the immediate approach. The third side of the triangle (later to become known as the Rose Street Curve) was formed by adaptation of the existing Harbour Branch.

In fact most passenger trains arriving from the north line ran past the station and reversed into the eastward-facing (i.e. towards the Perth line) platforms, so facilitating connections for passengers and also promptly releasing the train engine.

Dingwall to Invergordon The line between Inverness and Dingwall opened to the public on 11 June 1862.John Thomas and David Turnock, A Regional History of the Railways of Great Britain: Volume 15: North of Scotland, David & Charles (Publishers), Newton Abbot, 1989,

A number of small railway companies east of Inverness, including the Inverness and Nairn, had amalgamated and the Inverness and Aberdeen Junction Railway had been created. The construction north of Dingwall was continuing, and while it did so, the Inverness and Ross-shire Railway was absorbed by the Inverness and Aberdeen Junction Railway, by the Inverness and Aberdeen Junction Railway Act 1862 (25 & 26 Vict. c. cxiii) of 30 June 1862. At this point £83,000 of the authorised £245,000 capital of the Ross-shire company had been paid up.

The line between Dingwall and Invergordon was finally ready, and it too opened, on 25 March 1863.According to Vallance, Clinker, and Lambert, page 32. Ross says on page 34 23 May 1863; Thomas and Turnock say 25 May 1863 on page 316. Quick says 23 March 1863 (at various station entries.) The Invergordon station was close to the shore of Cromarty Firth.

Invergordon to Bonar Bridge

In the parliamentary session that year, the Inverness and Aberdeen Junction Railway (Bonar Bridge Extension) Act 1863 (26 & 27 Vict. c. xxxii) was passed, on 11 May 1863, authorising extension of the line to Bonar Bridge, a further .

The extension railway was opened to a station called Meikle Ferry, beyond Tain, on Dornoch Firth on 1 June 1864. The station closed in 1868 after the line advanced. The station buildings still exist (2015) as 'The Dornoch Bridge Inn' (now closed). The ferry crossing led to a coach connection which was laid on from Meikle Ferry to towns and villages in Sutherland and Caithness but the ferry was nearly into the Dornoch Firth from the station, and journeys north were inconvenient.

The line was opened to Bonar Bridge on 1 October 1864, but this station too was some distance from the place it purported to serve; the station was located on the south side of the Kyle of Sutherland, in a village slightly to the south called Ardgay.

Railway amalgamations were still on the agenda, and the Highland Railway was formed by merging the Inverness and Aberdeen Railway and the Inverness and Perth Junction Railway; the Highland Railway Act 1865 (28 & 29 Vict. c. clxviii) authorising this received royal assent on 29 June 1865.

The Sutherland Railway

The next stage of the Far North line was built by the Sutherland Railway, authorised by the Sutherland Railway Act 1865 (28 & 29 Vict. c. clxix), also on 29 June 1865. It continued from Ardgay along the south shore of the Kyle, crossing northwards at Invershin to Lairg (which became the railhead for the north western districts of Northern Scotland), then turning east to Golspie and Brora on the eastern sea coast. The new line was to be nearly long.

Successive Dukes of Sutherland had taken an interest in improving the districts they owned, and the Third Duke took a great interest in promoting the line. The Highland Railway reluctantly made a contribution of £30,000 to the construction costs of the line, after considerable pressure and manipulation by the Duke. Costs were exceptionally heavy due to the difficult terrain; the issue of the supposedly excessive cost of construction was made into a point of contention by the Duke at the time and subsequently.

Notwithstanding the cash injection, the company only managed to open as far as Golspie, which it did on 13 April 1868; Golspie was short of the intended terminal point at Brora. The Highland Railway operated the lines, which to outward appearances simply formed a continuous line from Inverness to Golspie.

There was a local gold rush in 1868 when two tributaries of the river near Kildonan were considered to have commercial gold reserves; the frenzy was known as the Sutherland Gold Diggings but they came to almost nothing. There was a repeat, equally unsuccessful, in 1896.

The Duke of Sutherland's Railway

Observing that the railway construction has stopped short — his seat at Dunrobin Castle was north of Golspie — the Duke of Sutherland obtained legal powers from Parliament to build a line from Golspie to Helmsdale. The Duke of Sutherland's Railway Act 1870 (33 & 34 Vict. c. xxxi) was passed on 20 June 1870, including the transfer of the powers for the section between Golspie and Brora to his new line. As he owned much of the land he was able to start construction in advance of the passage of the act. The railway was entitled the Duke of Sutherland's Railway.

Construction was easy except for short sections at each end of the line, and the central section was ready by the end of 1870. Accordingly, it was opened on 1 November 1870 between Dunrobin and a temporary station called West Helmsdale, less than a mile short of Helmsdale itself. A train service of two trains each way daily operated. As the line was not connected to the Sutherland Railway yet, an engine and rolling stock, hired from the Highland Railway, had to be taken to Dunrobin by road, hauled there by traction engines.

On 19 June 1871 the remaining railway construction was completed and the line was open throughout to Helmsdale; the Highland Railway took over the working of the line. The temporary terminus at Dunrobin became a private station for the Dunrobin estate.

In 1870 the Dingwall and Skye Railway opened the main part of its line, from a junction with the Far North Line at Dingwall to Stromeferry.

Reaching Caithness

In 1866 the Caithness Railway had been authorised by the Caithness Railway Act 1866 (29 & 30 Vict. c. ccxcii) to build a line joining the towns of Wick and Thurso. The territory southwards from those towns was desolate and mountainous, and there was no intention at the first stage, to connect the line to any other railway, although a line south to Helmsdale was considered, running inland to avoid the most difficult terrain. However the promoters of this line were unable to raise the subscriptions necessary to start construction, amid considerable posturing and offers of funding conditional on other people's contributions, and the idea fell into abeyance.

Inspired by the Duke of Sutherland's efforts in constructing a line to Helmsdale, a new company, the Sutherland and Caithness Railway, was promoted, obtaining its authorising act of Parliament, the Sutherland and Caithness Railway Act 1871 (34 & 35 Vict. c. xcix), on 13 July 1871. It was to adopt the authorised route of the defunct Caithness Railway, and to follow the inland route north from Helmsdale to connect to Wick and Thurso.

This was highly controversial, as the people of Wick expected a direct route over the Ord of Caithness to be followed; this would have been a much shorter route, and it would have made their town the focus of the northern lines. Such a route would have had challenging gradients: at 1 in 40 among others; one proposal would have had a rope-worked incline. Although serving significant coastal communities it would not have opened up the interior. Nonetheless the Caithness Railway interest continued to press its case, arguing against the increasingly determined view of the Duke of Sutherland that an inland route should be built. The two alternative supporters presented rival bills for the 1871 session of Parliament, but it immediately became evident that the Caithness Railway interest was unable to show the public benefit of the inland route, and the Sutherland and Caithness Railway Act 1871 (34 & 35 Vict. c. xcix) was passed on 13 July 1871; the Caithness Railway was no more.