Known for most of its length as Collierstown Road, the state highway runs 9.95 miles (16.01 km) from SR 672 and SR 770 in Collierstown north to U.S. Route 11 (US 11) and US 11 Business in Lexington.

After following the latter creek, SR 251 has a winding ascent out of the stream valley.

When Thornhill Road veers northeast toward downtown Lexington, SR 251 continues along Link Road the short remaining distance to its northern terminus at US 11 (Lee Highway) and US 11 Business (Main Street) southwest of downtown Lexington.

It used what is now SR 770 Turnpike Road to get to its current western end in Collerstown.

This section was removed on or by May 1945, presumably due to the difficult drive around North Mountain.