Sweeny is at the intersections of Texas Farm to Market Roads 1459 and 524, along the Missouri Pacific Railroad, twenty miles southwest of Angleton, in west central Brazoria County.

[5] The Union Pacific Railroad cuts a path through a small piece of the south side of Sweeny, with two grade crossings and a railyard.

The Sweeny Hospital District was established by an act of the Texas Legislature in 1963 following a decade-long community effort to expand healthcare in the area.

It is licensed for 20 inpatient beds, and is a Level IV Trauma Center with a dedicated surgical suite.

Imla Keep, a doctor and member of Stephen F. Austin's Old Three Hundred colonists, received title to a league and labor of land that included the site of Sweeny on July 24, 1824.

The land was named for John Sweeny, a Tennessee colonist who arrived with family members and 250 slaves in the area in 1833.

He came after his sons, William Burrell and Thomas Jefferson Sweeny, had purchased land grants near the townsite.

John Sweeny settled nearby, and in 1835, purchased the original Imla Keep League from Varner and constructed a house on the site.

[5] The home, today the Sweeny Plantation, a Recorded Texas Historic Landmark, was occupied by original family members through the 1990s.

The plantation had its own sawmill, sugar house, cotton gin, blacksmith shop, commissary, and a kiln for brick manufacture.

Sweeny was briefly called Adamston when the St. Louis, Brownsville and Mexico Railway reached the area in 1905 and laid a side track lined with gardens to the community.

His Burton D. Hurd Industrial Land Company promoted ten-acre suburban garden farms in the area with the slogan, "Soil Richer Than the Valley of the River Nile" to prospective settlers.

[5] By 1914 the community had a hotel, a flour mill, three general stores, a cotton gin, a gristmill, a sawmill, and a population of 200.

In 1942, a government carbon black plant was built which was taken over by Phillips Petroleum, which developed the facilities into a refinery, natural gas liquids center, and petrochemicals complex with pipelines to markets in the eastern United States.