 For its entire length , SR 319 runs along the boundary between Darke County on the south side and Mercer County on the north side . SR 319 begins in downtown Burkettsville at a former railroad grade just west of Washington Street . Known as Main Street within Burkettsville , the route runs due east through the village 's central business district prior to entering a residential area where it intersects a few side streets . After leaving the village of Burkettsville , SR 319 becomes the boundary between Darke County 's Allen Township and Mercer County 's Granville Township . After a short distance through farmland , the highway comes to an end as it arrives at its junction with SR 118 . Continuing east after the route terminates is Darke – Mercer County Line Road . 
