The seat of Marion County
, Jefferson is located north of Marshall
on US 59 at Hwy 49 on the banks of Big Cypress Creek near Caddo Lake and Little Cyprus Bayou.
It was named for Thomas Jefferson when it was founded in the early 1840s by Allen Urquhart and Daniel Alley.
In 1991 a roughly forty-seven-block area containing fifty-six historic structures was listed in the National Register of Historic Places. In addition, some ten other buildings have been accorded National Register status, including the antebellum Excelsior Hotel and Planters Bank and Warehouse.
Every year Jefferson sponsors a three-day spring historic pilgrimage to view these sites.
In 1990 the population was 2,199.