Daviess County is a county located in the U.S. state of Missouri. As of the 2020 census, the population was 8,430. Its county seat is Gallatin. The county was organized December 29, 1836, from Ray County and named for Major Joseph Hamilton Daveiss, a soldier from Kentucky who was killed in 1811 at the Battle of Tippecanoe. The county includes the town of Jamesport, which has the largest Amish community in Missouri.