Dimmitt was established in 1891 as the county seat of Castro County and named for Rev. W.C. Dimmitt. The hard feelings after Dimmitt was selected over Castro City as the county seat led to a gunfight between Ira Aten, a retired Texas Ranger, and Andrew McClelland. A historical marker at the courthouse square commemorates the event.
Castro County excels in agriculture, producing large yields of corn, wheat, sunflowers, sugar beets and vegetables (potatoes, carrots, onions, cucumbers).
Dimmit is also home to the Ogallala Quilt Festival, as quilters from all over the world and visitors gather here the first weekend in April to enjoy food, fun, festivities and competition.