Washington-on-the-Brazos is a ghost town along the Brazos River in Washington County, Texas, United States. It was founded when Texas was still a part of Mexico, and the settlement became 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".
The delegates declared independence on March 2, 1836. Their constitution was adopted on March 16. The delegates worked until March 17, when they had to flee, along with the people of Washington, to escape the advancing Mexican Army. The townspeople returned after the Mexican Army was defeated at San Jacinto on April 21. Town leaders lobbied for Washington’s designation as the permanent capital of the Republic of Texas, but leaders of the Republic passed over Washington in favor of Waterloo, which later was renamed Austin.
Washington County was created by the legislature of the Republic of Texas in 1836 and organized in 1837 and Washington-on-the-Brazos became the county seat. Although the county seat moved to Brenham in 1844, the town continued to thrive as a center for the cotton trade until the mid-1850s, when the railroad bypassed it. The strife of the Civil War took another toll on the town, and by the turn of the century it was virtually abandoned.
The State of Texas purchased 50 acres (202,000 m²) of the old townsite in 1916 and built a replica of the building where the delegates met. The state acquired more of the site in 1976 and 1996. The area, located at 30.324° -96.153° between Brenham and Navasota off State Highway 105, is now a state historic site with a better replica of the meeting hall and a museum with a research library.