Running for just over 5.5 miles (8.9 km) in a general east–west direction and completely with in Clay County, along the Historic National Road.

In Brazil SR 340 ends at an intersection with US 40 and the National Road continues east on US 40.

The entire route of SR 340 is along the old National Road and closely parallels US 40 to the north.

[2][3] The highest traffic count for SR 340 in 2016 was west of its intersection with Waterworks Road in Brazil, where 3,684 vehicles travel the highway on average each day.

The lowest traffic count during 2016 was at the western end of SR 340, where 1,379 vehicles travel the highway on average each day.