LONS-LE-SAUNIER, a town of eastern France, capital of the department of Jura, 76 m. N.N.E. of Lyons on the Paris-Lyons railway, on which it is a junction for Chalon-sur-Saône, Dôle, Besançon and Champagnole. Pop. (1906) 10,648. The town is built on both sides of the river Vallière and is surrounded by the vine-clad hills of the western Jura. It owes its name to the salt mines of Montmorot, its western suburb, which have been used from a very remote period. The church of St Désiré, a building of the 12th and 15th centuries, preserves a huge Romanesque crypt. The town is the seat of a prefect and of a court of assizes, and there are tribunals of first instance and of commerce, a chamber of commerce, lycées and training-colleges for both sexes, and a branch of the Bank of France. There is an establishment for the use of the mineral waters, which are sodio-chlorinated and have strengthening properties. The principal industry of the place is the manufacture of sparkling wines, the Étoile growth being the best for this purpose. Trade is in cheese, cereals, horses, cattle, wood, &c.
Lons-le-Saunier, known as Ledo in the time of the Gauls, was fortified by the Romans, who added the surname Salinarius to the Gallic name. An object of contention owing to the value of its salt, it belonged for a long time during the medieval period to the powerful house of Chalon, a younger branch of that of Burgundy. It was burned in 1364 by the English, and again in 1637, when it was seized by the duke of Longueville for Louis XIII. It became definitively French in 1674. It was here that the meeting between Ney and Napoleon took place, on the return of the latter from Elba in 1815. Rouget de l’Isle, the author of the Marseillaise, was born at Montaigu near this town, where there is a statue erected to him.