The Saulx (French pronunciation: [so]) is a 115 km long river in France, right tributary of the Marne.[1] Its source is near the village Germisay. It flows generally northwest, through the following départements and towns:

The Saulx flows into the Marne in Vitry-le-François. Its main tributaries are the Ornain and the Chée. The part of the Marne-Rhine Canal between Vitry-le-François and Sermaize-les-Bains runs parallel to the Saulx.

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