On 13 March 1839, the Louisiana Legislature passed the Act that officially created Union Parish, Louisiana from the northwestern corner of Ouachita Parish. Union Parish lies along the Arkansas border, in the upland hills region between the Ouachita and Red Rivers of northern Louisiana. It is located on the central axis of the state, as the north/south Louisiana Meridian bisects the parish. Union Parish consists primarily of gently rolling hills, once cloaked in towering loblolly pines. In fact, the earliest settlers called the southern portion of the parish the Pine Hills.

The rolling pine-topped hills form a distinguishing feature of the topography and flora of the west side of the Ouachita River, notably different from the flat prairies and cane breaks on the east side of the river. Numerous cypress sloughs dot the landscape of Union Parish, especially along the various bayous and creeks that crisscross the countryside. Union Parish has remained something of an isolated and rural area since the earliest European settlement, with a population that has never exceeded 25,000.

The Ouachita River forms the eastern border of the parish, and so Union Parish lies to the immediate west of the Mississippi Alluvial Plain, otherwise known as the Mississippi Delta. Whereas the rich, black ground of the delta region contains some of the most fertile soils on earth, most of Union Parish consists of sandy soil peppered with deposits of red, sticky clay. This distinct soil type led to the development of a culture quite different from that found in the Delta parishes across the Ouachita.

The wealthy planters who settled in the alluvial prairies between the Mississippi and Ouachita Rivers in the 1790s and early 1800s bypassed the pine hills on the west side of the Ouachita. Because the region did not readily lend itself to large-scale plantation agriculture, they showed little interest in settling the area, where Choctaw communities continued to occupy settlements along Bayou Corney until around 1830. As a result, the region that became Union Parish did not experience significant settlement until the late 1830s, after federal surveys had progressed sufficiently to allow widespread land sales to settlers.

Beginning in 1835, the federal government put the lands in north-central Louisiana on the market for cash purchase by citizens. Over the next quarter century, thousands of yeoman farmers from Mississippi, Alabama, Georgia, and Tennessee flocked to the region that later became the hill parishes of Union, Claiborne, Jackson, Bienville, and Lincoln on the west side of the Ouachita River. These small farmers possessed considerable expertise cultivating soils similar to those in this region. They cleared fields and began planting cotton as their primary cash crop and "Indian corn," sweet potatoes, and other garden vegetables as the primary sustenance crops. Throughout the antebellum period, the majority of early settlers worked their land themselves, without the use of slave labor. Even the minority of slaveholding Union Parish farmers owned only a few enslaved people, as the parish contained relatively few plantations and far fewer large slaveholders than the Delta parishes.

The pages below include links to various information on early Union Parish settlers and history: