In 1938, the newly-completed
Jorvaksentie road running west from Helsinki and its extension to Hanko via Kirkkonummi, Inkoo and Tammisaari was named main road 51. The road was realigned in 1944 because the previous route ran through the
Porkkala Naval Base that had been leased to the Soviet Union under the terms of the
Moscow Armistice. The route was moved to bypass the leased area, so it ran along the eastern shore of Espoonlahti Bay along the current
Old Saunalahdentie and
Kurttilantie to Kauklahti and further along current link road 1130 to Lapinkylä, Siuntio and the south of Virkkala. At Virkkala the road connected with main road 53 (now
national road 25). Later the road lost its status as a main road, but when the new section from Kirkkonummi to Karis was completed in 1972, the main road 51 designation was restored. The first motorway section of main road 51, then
Jorvaksentien, was completed to the west of Lauttasaari shortly before the mid-1960s, and the connection to Helsinki opened after the completion of the Lapinlahti Bridge in 1965. Before this, only a low-capacity 1930s bridge was in use. The motorway to Espoonlahti was completed in the late 1960s. The road between Kivenlahti and Kirkkonummi in Espoo used to be a congested two-lane road. In March 2010, construction work on a new motorway began and was completed on 29 October 2013. == Route ==