Simplon
a mountain of the Alps, in the S. of Switzerland, separating the canton of Valais from the Piedmontese territory. The old road across it being impracticable for heavy carriages, a new one, called the Route of the Simplon, was formed by order of Napoleon I. at the joint expense of France and the kingdom of Italy. Though the ascent is everywhere gradual, the highest point of the road is nearly 6,600 feet above the level of the sea. The length is 38 miles, and the width between 25 and 30 feet. It is carried through several tunnels, over upward of 600 bridges, and has 20 station houses for travelers. The road of the Simplon, long regarded as one of the greatest teats accomplished by modern engineering, has become of less importance since the formation of a railroad. The Simplon tunnel, completed in February, 1905, is larger than either that of St. Gothard or Mt. Cenis. It is 122 miles long as against 8 miles for the Mt.
Cenis and 9.3 miles for the St. Gothard.