It is bisected by the Arkansas River, which was critical to its development and long the chief transportation byway.

The area now known as Jefferson County was occupied by the Quapaw when Henri de Tonti established Arkansas Post in 1686.

[citation needed] Several years later, James Scull, also from Arkansas Post, established a tavern and small inn on the river's north bank, across from what would become the site of Pine Bluff.

[5] Steamboat travel led to expanding settlement, bringing to the area such men as French Peninsular War veteran and Indian trader Antoine Barraque (a township in northwest Jefferson County and Pine Bluff's principal east–west street are both named for him) and brothers James T. and John Pullen (main thoroughfares are both named for them).

Though Bonne's cabin was initially used; by August 1832, "Pine Bluff Town" became the permanent county seat.

"[5] The land in the county was developed as large cotton plantations, with fronts on the river for transportation.

[citation needed] After the war, planters in Jefferson County gradually resumed cotton cultivation and processing.

[citation needed] The economy was driven by cotton and the Delta area was highly productive.

[23][24][25] The administrative Annex East is on Harding Avenue in Pine Bluff, south of city hall.

[31] The Maximum Security Unit is 25 miles (40 km) north of central Pine Bluff and off Arkansas Highway 15 in unincorporated Jefferson County.

[34] Jefferson County is strongly Democratic in races for president, governor, and the United States Senate.

In the Reconstruction Era, the county's majority black residents favored presidential candidates from the Republican Party in every election from 1868 to 1888.

[citation needed] In the early 1890s, white Southern Democrats passed laws to disenfranchise black voters from engaging in the political process, a process which ended by the 1960s, and blacks began to favor voting for Democrats and southern whites favored the Republicans.

Each township includes unincorporated areas; some may have incorporated cities or towns within part of their boundaries.

However, the United States census does list Arkansas population based on townships (sometimes referred to as "county subdivisions" or "minor civil divisions").

Each town or city is within one or more townships in an Arkansas county based on census maps and publications.