[3] The name is pronounced as in "mole tree", unlike the pronunciation of its namesake, the South Carolinian Revolutionary War hero William Moultrie.

It is named for South Carolina General, and later Governor, William Moultrie.

General Moultrie defended Sullivan's Island, South Carolina from British attack in 1776.

When Abraham Kellar of Lovington, John Cook of Marrowbone, and John Fleming of Nelson proposed the formation of a new county from Macon, Shelby, and Coles counties, Macon gave up a strip of “worthless swamp” that is now among the most fertile land in the world, but Shelby and Coles voters refused to give up any land.

[5] As of the 2010 United States Census, there were 14,846 people, 5,758 households, and 4,053 families living in the county.

Moultrie County voters have voted for the Republican Party candidate in eight of the last ten national election campaigns.