In 1821, Hersfeld became the seat of Hersfeld district in the Electorate of Hesse. In the same century, Hersfeld was linked to the railway network in 1866, and the town has also had an Autobahn link since 1938 (today Bundesautobahn 7) northwards via Kassel and Hamburg to Scandinavia and southwards via Kirchheim, Baden-Württemberg and Bavaria to Austria. The Bundesautobahn 4 coming from Kirchheim links eastwards via Dresden and Görlitz to Poland. The development into a spa town began when the Lullusbrunnen (spring) was tapped in 1904.