The land and springs around this site made it a favored camping site for local Indian tribes for centuries before the Spanish discovered it. Raids, drought and conflict led the Spanish to abandon the area in 1756. The Mexican state of Coahuila and Texas granted a colonization contract to Robert Leftwich in 1825. Conflicting contracts were granted to Stephen F. Austin and Sterling C. Robertson. George W. Glasscock, Sr. (1810-1868) purchased the land while speculating for Thomas B. Huling and Company. In 1839 Glasscock received two headrights including this land as part of his share of assets when the company dissolved.
The site had become a popular gathering place for settlers when Sam Houston spoke here in 1859. It became known as "The Fairgrounds." Large annual fairs, reunions and religious revivals drew crowds from surrounding areas. The county's first public hanging took place here in 1886, Williamson County Old Settlers' Association, formed in 1904, used the area for Annual Gatherings, eventually leasing 33 acres and building reunion structures. Helen Glasscock, the widow of George Glasscock, Jr., sold the site to I.M. Williams in 1912. A devastating flood in 1921 swept away the fairgrounds.
Georgetown citizens requested that the city buy the site from the Williams family and name it San Gabriel Park in 1933. Under the direction of R.E. Ward, the city improved the park in the 1930s and 1940s. A river wall, low water crossing, large building and rest rooms were erected with funding and labor from the Federal Works Progress Administration. Rodeo pens, sports fields and further land acquisitions continue to ensure that the park provides recreation and shelter for area citizens.