Washington-on-the-Brazos is an unincorporated area along the Brazos River in Washington County, Texas, United States. Founded when Texas was still a part of Mexico, the settlement was the site of the Convention of 1836 and the signing of the Texas Declaration of Independence. The name "Washington-on-the-Brazos" was used to distinguish the settlement from "Washington-on-the-Potomac"—i.e., Washington, D.C.