US 31A begins in
Giles County in
Pulsaki at an intersection with
US 31 (
SR 7) just north of downtown. It winds its way northeast through the hilly terrain of the
Highland Rim for several miles to cross into
Marshall County at an interchange with
I-65 (Exit 22). The highway then passes through the town of
Cornersville, where it has a long concurrency with
SR 129, before continuing northeast to enter
Nashville Basin and the city of
Lewisburg at an intersection with
US 31A Business. Here SR 11 splits off and follows US 31A Business through downtown while US 31A follows a bypass route to the east (
SR 106). It passes through neighborhoods before becoming concurrent with
SR 272 and passing through a mix business and industrial areas. The highway then becomes concurrent with
US 431 at an intersection with
US 431 Business (
SR 50) and they curve to the northwest to cross a bridge over a creek before coming to another intersection with US 31A Business/US 431 Business (SR 11), where US 31A, SR 11, and SR 272 split off and head northeast, with SR 272 splitting off shortly thereafter. US 31A continues northeast through farmland for several miles to pass through the community of
Farmington, where it has an intersection between
SR 64 and
SR 271, before crossing the
Duck River at
Henry Horton State Park. It then enters the city limits of
Chapel Hill, where it becomes concurrent with
SR 99 and has an intersection with
SR 270, before passing through downtown. SR 99 splits off and goes east shortly thereafter and US 31A then leaves Chapel Hill and passes through rural farmland for several miles to cross into
Williamson County. US 31A straddles the county line with
Rutherford County for several miles, where it passes through the community of
Allisona and has an intersection with
SR 269, before re entering Williamson County to pass through the communities of
College Grove and
Kirkland, where it becomes concurrent with
US 41A (
SR 16) and crosses over the
Harpeth River. US 31A/US 41A head north to pass through the community of
Triune, where they have an interchange with
I-840 (Exit 42) and have an intersection with
SR 96, before passing through some hills to pass through the town of
Nolensville and cross into
Davidson County. The highway immediately enters the
Nashville city limits and passes northwest through suburban areas for several miles as Nolensville Pike, where it has intersections with
SR 253 (Concord R,
SR 254 (
Old Hickory Boulevard),
SR 255 (Harding Place), and
SR 155 (Thompson Lane), as well as crossing over
Mill Creek and
Sevenmile Creek. US 31A/US 41A then begin passing through business districts as it has an interchange with
I-440 (Four-Forty Parkway; Exit 6) before the highway splits into a one-way pair between 4th Avenue S and 2nd Avenue S. They then become concurrent with
US 41/
US 70S (
SR 1/Lafayette Street) at an interchange with
I-40 (Exit 210C). They turn west for a short distance before US 31A comes to an end at an roundabout with US 31 (
SR 6/8th Avenue S). ==Major intersections==