 SR 109 immediately enters Gallatin and widens to a 4-lane undivided highway and passes through a business district before coming to an intersection with Airport Road, where it turns left onto a bypass of downtown, where it becomes a divided highway once again.SR 109 then passes several neighborhoods before having an interchange with US 31E/SR 6.It then has an interchange with SR 174/SR 386 before having an at-grade intersection with SR 25 and leave Gallatin.