Östergötland County is a county or län in southeastern Sweden. It has land borders with the counties of Kalmar to the southeast, Jönköping to the southwest, Örebro to the northwest, and Södermanland to the northeast. It also has a sea border with Västra Götaland to the west, and borders the Baltic Sea to the east.

Jönköping County is a county or län in southern Sweden. It borders the counties of Halland, Västra Götaland, Östergötland, Kalmar and Kronoberg. The total county population was 356,291 inhabitants in September 2017. The capital and largest city is Jönköping. About one quarter of the total county population lives in the combined Jönköping-Huskvarna urban area around the southern point of Lake Vättern.