During the Middle Ages Zweisimmen grew into a local center for trade and government. In 1644 the annual fair was moved to Zweisimmen and brought cattle and cheese buyers from Italy and Germany to the municipality. In the 1750s a trade route from Thun to Montreux was built into Zweisimmen. The Simmental road was built from Saanen into the Simmen valley in 1816-45. The new road brought additional trade and eventually tourists to the municipality. A hotel was built in 1881. The completion of the Spiez-Zweisimmen-Montreux railroad in 1905 opened the villages up to many additional tourists. The hotel became a spa and resort in 1912 and included winter sports in 1920. The municipal tourism industry was devastated by the Great Depression and World War II. However, it began to recover in the 1950s with many new cable cars and ski lifts. Zweisimmen cooperated with the neighboring tourist municipalities of Gstaad, Lenk im Simmental and Adelboden to build extensive ski resorts along with an airfield.