Ohio State Route 320

State Route 320
Route information
Maintained by ODOT
Length	3.12 mi[1] (5.02 km)
Existed	March 9, 1932[2]–present
Major junctions
South end	US 35 near New Paris
Major intersections	US 40 near New Paris
North end	SR 121 in New Paris
Location
Country	United States
State	Ohio
Counties	Preble
Highway system
Ohio State Highway System Interstate US State Scenic
← SR 319 → SR 321

State Route 320 (SR 320) is a short north–south state highway in western Ohio, a U.S. state. The southern terminus of SR 320 is at U.S. Route 35 (US 35) approximately three miles (4.8 km) southeast of New Paris, 3⁄4 mile (1.2 km) south of US 35's eastern junction with Interstate 70 (I-70). The northern terminus of the state highway is located in New Paris at a signalized intersection with SR 121.

This L-shaped two-lane highway was first designated in the early 1930s along the stretch between Preble County Road 335 (CR 335) and SR 121. The highway was extended some three decades later along the former US 35 to its current southern terminus when the U.S. highway was re-routed onto the newly constructed I-70 freeway nearby. The north–south portion of SR 320 between New Westville and New Paris runs in parallel to the east of the Indiana state line by a distance of just more than one mile (1.6 km). No direct access is provided between SR 320 and I-70/US 35. Consequently, one may access I-70 westbound from SR 320 via US 35. To get to I-70 eastbound from SR 320, one must follow CR 335 westbound into Indiana, where it becomes known as Eaton Pike, and connect to US 40 to access the freeway in the eastbound direction.