Finland–Russia border

Between Sweden and Russia

For centuries Finland was a buffer between Sweden, which began to settle southern Finland around 1300, and Russia. Sweden pushed east and in 1617, by the Treaty of Stolbova, took Karelian districts north of Lake Ladoga. The Treaty of Nystad in 1721 gave them back to Russia along with the Finnish area of Viipuri (Vyborg), and another war moved the line west again in the 1740s.^[3]

The last Russo-Swedish war ended in 1809 with the Treaty of Hamina and the cession of all of Finland to Russia. Tsar Alexander I made it a Grand Duchy with its own constitution, and in 1811 gave Viipuri back to it. From 1809 to 1917 the line was an internal boundary of the Russian Empire.^[3]

Independence and the Treaty of Dorpat

The Finnish Diet declared independence on 6 December 1917, and Russia recognised it on 4 January 1918.^[3] The Treaty of Dorpat (Tartu), signed on 14 October 1920, confirmed the old Grand Duchy’s border and gave Finland the Petsamo region, which Finns said the tsars had promised them for access to the Arctic Ocean. In return Finland dropped its claim to Russian Karelia.^[3]

Mixed commissions surveyed and marked the whole line over the next two decades, with pillars numbered from 1 on the Gulf of Finland to 919 on the Arctic Ocean, and the final protocol was signed on 28 April 1938.^[3]

Two wars, two new lines

In 1939 the Soviet Union demanded territory in Karelia and the north and a naval base at Hanko. Finland refused, and the Winter War began on 30 November 1939. The Treaty of Moscow of 12 March 1940 took about 16,100 square miles (41,700 km²) of Finland: Viipuri and Ladoga Karelia, Salla, and part of the Rybachi peninsula. Finland lost land home to 10% of its people, and its major port, Viipuri.^[3]

When Germany attacked the Soviet Union in 1941, Finland went back to war and retook its old borders. By 1944 it had to sue for peace again. The armistice of 19 September 1944 restored the 1940 line in the south and centre and gave the whole of Petsamo back to the Soviet Union, cutting Finland off from the Arctic Ocean.^[3] The Paris peace treaty of 10 February 1947 confirmed it, and a treaty signed a week earlier moved a small area around the Janiskoski hydroelectric station on the Pasvik river to the Soviet Union, to power the mines at Nikel.^[3]

“The frontiers of Finland, as shown on the map annexed to the present Treaty (Annex I), shall be those which existed on January 1, 1941, except as provided in the following Article.”^[3]

A line of straight lines

The border is drawn mostly as straight lines between turning points and ignores the landscape. In Karelia, rivers form only 25 of its 251 miles, and north of Salla it is entirely straight lines, most over 15 miles long. Near the Norwegian tripoint it jogs west and back to put the Janiskoski power site inside Russia.^[3] In 1967 the US Geographer noted the whole line had been marked on the ground by mixed commissions.^[3]

Closed and fenced

In late 2023 Finland said Russia was deliberately sending migrants without visas to its border, nearly 1,000 between August and November, as a form of hybrid warfare; the Kremlin denied it. Finland closed the whole border at the end of November, briefly reopened two crossings on 14 December, and shut them again the next day.^[2] The road crossings have stayed closed indefinitely since then.^[4] On 1 July 2026 Russia closed its five railway checkpoints on the Finnish border, leaving no rail crossing open either.^[4]

Finland also built a fence. Work started with a pilot near Imatra in April 2023, and the 200 km of fencing, mostly in the southeast, was completed in September 2026 at a cost of about €380 million. It covers only part of the border, which Yle calls the longest that any EU or NATO country shares with Russia.^[1]