1 Prior to 1658 it was known as the County of Karelia (Swedish: Karelens län, Finnish: Karjalan lääni).
Viborg and Nyslott County (Swedish: Viborgs och Nyslotts län, Finnish: Viipurin ja Savonlinnan lääni) was a county of the Swedish Empire from 1634 to 1721. The county was named after the castle towns of Viborg (Finnish: Viipuri) and Nyslott (Finnish: Savonlinna, literally New Castle), today located in the towns of Vyborg in Russia and Savonlinna in Finland.
The county was established in 1634 as Karelia County (Swedish: Karelens län, Finnish: Karjalan lääni), but in 1641 Nyslott County (Swedish: Nyslotts län, Finnish: Savonlinnan lääni) was broken out and made a separate entity. Remainder of Karelia County was now called Viborg County. In 1650 the counties were joined again as the Viborg and Nyslott County.