The 1,200-acre San Jacinto Battleground State Historic Site is a National Historic Landmark. It has three units:

The developed park (about 500 acres) was acquired in parcels from 1899 to the 1930s. This area holds the monument and pool, battleground and picnic sites, Battleship Texas, and other facilities. The monument was completed in 1939. Battleship Texas arrived here in 1948.

The marsh unit (300 acres) lies to the north of the developed park area.

The forest unit (about 200 acres) provides a buffer between the park and the petrochemical plants on the south side of the park.