Lawrence County is known as the "Mother of Counties" because 31 of Arkansas' present counties were carved from the original Lawrence County.

Named for Captain James Lawrence, a naval officer killed in the War of 1812, the county was the second formed by the Missouri legislature, which had jurisdiction over the region until Arkansas became a territory in 1819. When created on January 15, 1815, Lawrence County covered more than half of the present state, plus a strip across the southern part of Missouri. Davidsonville, the site of the first Arkansas post office, land office, and courthouse, was the original county seat of Lawrence County.

The seat of justice was moved three times before relocating to Powhatan in 1869. With the completion of the railroad through eastern sections of the county, Walnut Ridge also became a county seat. Lawrence County maintained dual courthouses until 1963, when it reverted to the single-district plan and Walnut Ridge became the sole county seat.