Washington County was the tenth county formed in Georgia. It was created February 25, 1784 from Creek Indian lands. It then included all the territory from the Cherokee Corner, north, extending from the Ogeechee to the Oconee, south to Liberty County. The first settlers were Revolutionary War Veterans who won land grants for their service. In 1786 a portion of it was added to Greene; in 1793, a part to Hancock; in 1807, a part to Baldwin; in 1811, a part to Laurens; and in 1812 and 1826, more to Baldwin. Today seven counties plus portions of nine others were originally part of Washington County.
Warthen was the first settlement in Washington County and the first church in the area was constituted in 1790. Saunders Crossroads located at the crossing of two Indian trails was named the County seat in 1796. It eventually became known as Sandersville.