1939 along its current path, which extended another mile to the south.

This section, from the new route of US 287 south to the old location of US 287, was removed on November 29, 1990, as portions of the route and US 287 were submerged by the newly impounded Richland Chambers Reservoir.

SH 309 begins at boat ramp 0.5 miles (0.8 km) south of US 287 on the Richland-Chambers Reservoir and heads north to a junction with US 287.

It heads northwest from this junction to an intersection with FM 635.

Heading towards the northwest, the highway continues to an intersection with FM 3096 in Kerens.