Kentucky State Route 139 runs north-south across the center of Caldwell County. It runs from the tri-point of Trigg/Caldwell/Lyon County Line, near southeast of Lamasco to the Caldwell/Crittenden County Line, west of Marion. KY St Rt 139 passes through the following town in Caldwell County. Princeton
KY St Rt 139 is multi-plexed with the following highways in Caldwell County. Kentucky State Route 514, near Lamasco. Kentucky State Route 293, at Princeton.