Karelian Isthmus

Karelian Isthmus, land bridge in northeastern Europe, between the Gulf of Finland on the west and Lake Ladoga on the east, connecting Finland with Russia. Forests and marshes cover most of the isthmus, which is 145 km (90 mi) long and from 40 to 110 km (25 to 70 mi) wide. All of it except for the southernmost section belonged to Finland until 1940, when a Soviet-Finnish peace treaty transferred the whole region to Soviet control. In 1944 the isthmus was incorporated into the Leningrad Oblast of Russia. Its chief cities are Saint Petersburg and Vyborg.