Viken is a county under disestablishment in Eastern Norway that was established on 1 January 2020 by the merger of Akershus, Buskerud and Østfold with the addition of the municipalities of Jevnaker, Lunner and the former municipality of Svelvik. Viken was controversial from the onset, with an approval rating of about 20% in the region, and the merger was resisted by all the three counties. Viken has been compared to gerrymandering. The county executive of Viken determined in 2019, before the merger had taken effect, that the county's disestablishment is its main political goal, and the formal process to dissolve Viken was initiated by the county executive in right after the 2021 Norwegian parliamentary election in which parties seeking to reverse the merger won a majority. The political platform of the government of Jonas Gahr Støre states that the government will dissolve Viken and re-establish Akershus, Buskerud and Østfold based on a request from the county itself. On 22 February 2022, the regional assembly of Viken approved the formal request to disestablish the county, which will come into effect on 1 January 2024. The existing counties will continue to function with separate county administrations based on their existing infrastructure in anticipation of their formal re-establishment.
Viken was home to over 1.2 million people, or 23% of the national population. The county seat is the national capital, Oslo, which is an enclave of Viken and is not part of the county. Oslo had been the seat of Akershus county since the Middle Ages. All of Viken is located in the historical Akershus, which included much of Eastern Norway. The county takes its name from the historical region of Viken, which has been defined as an area in Bohuslän, in what is now western Sweden, since the Middle Ages.