State Route 9 (SR 9) is a north–south route running through four counties in east central Ohio. Its route is 92.5 miles (148.9 km) long. The southern terminus is at SR 148 in Armstrongs Mills and the northern terminus is with US 62 north of Salem.

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• before 1931 – Route 9 ran from Cincinnati to Michigan. This highway followed the current U.S. Highway 127 from the Ohio River at Cincinnati to just south of Bryan and followed current Ohio State Route 15 northward to the Michigan state line.
• 1935 – New incarnation of route 9 certified; Originally routed from Malaga to Salem along current routes 145, 148, and 9.
• 1938 – Southern end truncated to Armstrongs Mills.
• 1974 – Northern end extended through Salem to 2 miles (3.2 km) north of Salem.

County	Location	mi	km	Destinations	Notes
Belmont	Washington Township	0.00	0.00	SR 148 (Captina Road)	Southern terminus
	Smith Township	5.94	9.56	SR 147 (Main Street)	Southern end of SR 147 concurrency
		6.71	10.80	SR 147 (Belmont–Centerville Road)	Northern end of SR 147 concurrency
		10.38	16.70	SR 149 (Belmont–Warnock Road)	Southern end of SR 149 concurrency
		10.51	16.91	SR 149 (Warnock–Glencoe Road)	Northern end of SR 149 concurrency
	Richland Township	14.53– 14.58	23.38– 23.46	I-70	Diamond interchange; exit 216 on I-70
	St. Clairsville	15.39	24.77	US 40 (Main Street)
Harrison	Athens Township	24.70	39.75	SR 149 (Flushing–New Athens Road)	Northern terminus of SR 149
	New Athens	25.24	40.62	SR 519
	Cadiz	31.90	51.34	US 250	Southern end of US 250 concurrency
		32.72– 32.90	52.66– 52.95	US 22 (Cadiz–Steubenville Road) / US 250	Northern end of US 250 concurrency; Partial cloverleaf interchange
	Rumley Township	39.94	64.28	SR 151 (Jewett–Scio Road)	Southern end of SR 151 concurrency
	Jewett	41.77	67.22	SR 151 (Main Street)	Northern end of SR 151 concurrency
	German Township	46.07	74.14	SR 646 (Annapolis Road)	Southern end of SR 646 concurrency
		46.66	75.09	SR 646 (Rumley East Road)	Northern end of SR 646 concurrency
Carroll	Loudon Township	51.13	82.29	SR 164 (Amsterdam Road)	Southern end of SR 164 concurrency
		51.19	82.38	SR 164 (Amsterdam Road)	Northern end of SR 164 concurrency
	Lee Township	56.40	90.77	SR 43 (Steubenville Road)	Southern end of SR 43 concurrency
	Center Township	61.28	98.62	SR 39 (Salineville Road)	Southern end of SR 39 concurrency
	Carrollton	61.79	99.44	SR 39 / SR 43 / SR 332	Northern end of SR 39/43 concurrences; Northern terminus of SR 332
	Washington Township	65.47	105.36	SR 171 (Waynesburg Road)
Columbiana	Hanover Township	76.76	123.53	US 30 / SR 644	Southern end of US 30 concurrency; Northern terminus of SR 644
	Hanoverton	78.30	126.01	US 30	Northern end of US 30 concurrency
	Hanover Township	81.51	131.18	SR 172
	Perry Township	88.81	142.93	SR 45
	Salem	90.47	145.60	SR 14 / SR 173	Southern end of SR 14 concurrency
		90.73	146.02	SR 14 / SR 344	Northern end of SR 14 concurrency
		92.51	148.88	US 62	Northern terminus at a T-intersection
1.000 mi = 1.609 km; 1.000 km = 0.621 mi       Concurrency terminus