Its main route, approximately 740 kilometers (460 mi) long, connected the capital, Berlin, with the cities of Danzig (now Gdańsk, Poland) and Königsberg (now Kaliningrad, Russia).

From about 1840, the Prussian military urgently sought a railway connection to the Russian border for strategic reasons.

The railway was also seen from the early years as a means of developing the underdeveloped areas of East Prussia and Pomerania.

A lack of interest from the private sector led King Frederick William IV to initiate in 1845 preparatory work for the construction of the Eastern Railway.

Construction was stopped, as the members of the provincial diet (Provinziallandtag) of East Prussia refused consent for the king to borrow for the project.

This vote was confirmed in the United Diet (Vereinigter Landtag), the first parliamentary body covering all of Prussia, which was convened in April 1847 and subsequently dissolved.

Members voted by a two-thirds majority against authorising a government loan for the Eastern Railway project.

Only the events of the March Revolution of 1848 and the appointment of banker August von der Heydt as the Prussian Minister of Commerce and Industry—and therefore responsible for railways—led to progress on the issue.

In August 1849, Von der Heydt laid before the diet a draft law for the construction of the Eastern Railway, which was adopted on 7 December 1849.

From this same station, the first 145 km long section of the Eastern Railway was built via Schneidemühl to Bromberg; this was opened on 27 July 1851.

Beyond the Nogat and Vistula rivers, the railway continued to be built from Marienburg via Elbing to Braunsberg (83.75 km); it was opened on 19 October 1852.

Berlin was therefore reached by a shorter route via the Lower Silesian-Märkische Railway (Niederschlesisch-Märkische Eisenbahn-Gesellschaft, NME).

One of his successors was Albert von Maybach (1863–1867), previously Chairman of the Board of the Upper Silesian Railway (Oberschlesische Eisenbahn).

In 1855, the Union-Gießerei (foundry) Königsberg began to build locomotives; the Schichau-Werke (works) of Ferdinand Schichau of Elbing followed its example in 1860.

The Königsberg agricultural equipment manufacturer L. Steinfurt built freight wagons and passenger carriages.

The Eastern Railway was at the time one of the major long-distance rail routes in Europe and one of the main axes for east–west traffic.

The Eastern Railway line became a major transit link between East Prussia and the rest of Germany.

The latter required a travel time of 6 hours and 36 minutes for the 590 kilometre long line from Königsberg to Berlin Silesian station.

Since 1991 the term Ostbahn (Eastern Railway) has again been used to appeal to the nostalgia of tourists wishing to travel along parts of the former line.

Substantial boundary changes were made as a result of the German defeat in World War II, so that the only part of the former Eastern Railway to remain in Germany is the section from Berlin to the Oder River near Küstrin.

The section within the current borders of Germany that connects Berlin with the Polish border near Küstrin-Kietz is now a largely single-track non-electrified main line, part of the tariff zone of the Verkehrsverbund Berlin-Brandenburg (Berlin-Brandenburg Transport Association) and has been operated by Niederbarnimer Eisenbahn since 10 December 2006 with Bombardier Talent diesel multiple units.

This did not affect travel times or the timetable, but the change is considered a sign of an incipient upgrade of the Eastern Railway.

The line in Poland from Kostrzyn to Piła is double track except for a short section at the eastern exit of Gorzów station.

Shortly afterwards another pair of tracks was added to the northern half of the Ringbahn to allow suburban trains to run independently of long-distance traffic.

The location of the intersection with the Ringbahn had insufficient space, so a new grade-separated junction was built on the main line from Frankfurt (Oder) 2 km away at Rummelsburg depot.

Since the Eastern Railway was a strategically important route on the basis of its orientation, work continued on this project despite the outbreak of the Second World War.