Wyoming Highway 789 (WYO 789) is a 407-mile-long (655 km) state highway in the U.S. state of Wyoming. WYO 789 travels south-to-north from the Colorado state line to the Montana state line. For most of its length, it is concurrent with other routes. It was the path of a formerly-proposed U.S. Route 789 that was canceled.

WYO 789 begins at the Colorado state line just south of Baggs. It travels north for about 4 miles (6.4 km) to Baggs. After Baggs, it continues north for about 45 miles (72 km) until it reaches the county line.

After crossing the county line, WYO 789 travels north for about 6 miles (9.7 km) where it reaches exit 187 of I-80/US 30. WYO 789 joins I-80/US 30 eastbound.

I-80/US 30/WYO 789 re-enter Carbon County. Just west of Rawlins, WYO 789 leaves at exit 211, joining I-80 Bus./US 30 Bus. through Rawlins. North of town, WYO 789 intersects US 287 and travels concurrent with it north for 50 miles (80 km) to the county line, after which it passes through Natrona County for about 2 miles (3.2 km).

US 287/WYO 789 continue in a northwest direction, passing through the towns of Jeffrey City and Sweetwater Station. About 40 miles (64 km) from Sweetwater Station, US 287/WYO 789 enter Lander. WYO 789 splits from US 287 here and continues northeast for 24 miles (39 km), alone, to Riverton. WYO 789 joins US 26 until they reach Shoshoni. Here, US 26/WYO 789 intersect US 20 where WYO 789 continues north with US 20 west.

US 20/WYO 789 continue through the Wind River Canyon into Thermopolis. From there, the highway veers off in a northeasterly direction into Washakie County. From the Washakie county line, the highway travels approximately 21 miles (34 km) before crossing the Big Horn River into Worland where it joins US 16/US 20.

Upon crossing into Big Horn County, US 16/US 20/WYO 789 veer back to the northwest and cross back over the Big Horn River after reaching Manderson. It continues on 20 miles (32 km) to the north through Basin and Greybull. Upon reaching Greybull, US 16/US 20/WYO 789 head west and join US 14 for about 5 miles (8.0 km).

At that point, WYO 789 separates from the concurrency of US 14/US 16/US 20 and returns to its northern path along with US 310 for about 28 miles (45 km) to the town of Lovell. For about 3 miles (4.8 km), US 310/WYO 789 travels west along US 14 Alt. US 310/WYO 789 then turn north for about 3 miles (4.8 km) to Cowley and then head west about 7 miles (11 km) to Deaver.

From Deaver, US 310/WYO 789 travel about 6 miles (9.7 km) north to Frannie, where they straddle the boundary between Big Horn County and Park County. Just to the north of Frannie, US 310/WYO 789 bends slightly to the west, so that the road is actually inside Park County by about 400 feet before reaching the Montana state line. At the state line, WYO 789 ends, while US 310 continues north.

U.S. Route 789
Location	Nogales, Arizona, to Sweet Grass, Montana
Existed	November 20, 1950–October 14, 1952

WYO 789 was part of a 1950s proposal for a border-to-border U.S. Route 789 that would have traveled from Nogales, Arizona, to Sweet Grass, Montana. After the US 789 proposal was rejected by AASHTO on 14 October 1952, US 789 became part of a series of state highways numbered 789 traveling along the proposed route. Wyoming, however, was the only state that actually applied the number exclusively to existing highways (but only in some sections), whereas the other states simply added a concurrent SR 789 over existing highways. Because of this, all the states except Wyoming eventually deleted the designation and removed the signs.

County	Location	mi	km	Destinations	Notes
Carbon	​	0.00	0.00	SH 13 south – Craig, Meeker, Rifle	Continuation beyond Colorado state line
	Baggs	2.52	4.06	WYO 70 – Dixon	Western terminus of WYO 70
Sweetwater	​	53.19	85.60	I-80 west / US 30 west – Rock Springs	Western end of I-80/US 30 concurrency; Exit 187 on I-80
Carbon	​	77.77	125.16	I-80 east / US 30 east / I-80 BL ends / US 30 Bus. ends – Cheyenne	Eastern end of I-80/US 30 concurrency; western end of I-80 Bus./US 30 Bus. concurrency; I-80/US 30, exit 211
	Rawlins	79.41	127.80	US 287 south / I-80 BL east / US 30 Bus. east – Laramie	Eastern end of I-80 Bus./US 30 Bus. concurrency; southern end of US 287 concurrency
	​	81.13	130.57	US 287 Byp.	Northern terminus of US 287 Bypass; southern end of Chief Washakie Trail
	​	112.47	181.00	WYO 73 – Bairoil	Eastern terminus of WYO 73
	​	123.52	198.79	WYO 220 / California National Historic Trail / Mormon Pioneer National Historic Trail / Oregon National Historic Trail / Pony Express National Historic Trail – Casper	Western terminus of WYO 220
Natrona	No major junctions
Fremont	​	165.63	266.56	WYO 135 – Riverton	Southern terminus of WYO 135
	​	195.82	315.14	WYO 28 / California National Historic Trail / Mormon Pioneer National Historic Trail / Oregon National Historic Trail / Pony Express National Historic Trail – Rock Springs	Eastern terminus of WYO 28
	Lander	204.00	328.31	US 287 north / Chief Washakie Trail north – Dubois, Teton, Yellowstone, Sinks Canyon State Park	Northern end of US 287 concurrency
	​	215.59	346.96	Ethete Road – Arapahoe	Former WYO 138
	Arapahoe	227.02	365.35	Ethete Road / Sand Creek Massacre Trail west – Arapahoe	Former WYO 137
		227.38	365.93	WYO 135 to WYO 136 (Gas Hills Road) – Rawlins, Castle Gardens	Northern terminus of WYO 135
	Riverton	228.73	368.11	US 26 west (Main Street) – Dubois, Yellowstone, Teton	Southern end of US 26 concurrency
	​	242.61	390.44	WYO 134 – Pavillion	Eastern terminus of WYO 134
	Shoshoni	250.87	403.74	US 20 east / US 26 east (2nd Street east) / Sand Creek Massacre Trail east – Casper	Northern end of US 26 concurrency; southern end of US 20 concurency
Hot Springs	​	280.62	451.61	WYO 173 (Buffalo Creek Road)	Western terminus of WYO 173
	Thermopolis	283.27	455.88	WYO 120 – Meeteetse, Cody, Wyoming Dinosaur Center	Southern terminus of WYO 120; access to Hot Springs Memorial Hospital
	Lucerne	290.55	467.59	WYO 172 (Black Mountain Road)	Western terminus of WYO 172
	Kirby	294.95	474.68	WYO 175 – Kirby	Western terminus of WYO 175
Washakie	​	307.28	494.52	WYO 431 west / WYO 432 east	Eastern terminus of WYO 431; southern terminus of WYO 432
	​	315.35	507.51	WYO 433	Southern terminus of WYO 433
	Worland	316.01	508.57	To WYO 432
		316.33	509.08	US 16 east – Buffalo	Southern end of US 16 concurrency; access to Washakie Medical Center
Big Horn	Manderson	334.98	539.10	WYO 31 – Manderson, Hyattville	Western terminus of WYO 31
	​	336.15	540.98	WYO 433	Northern terminus of WYO 433
	Basin	346.60	557.80	WYO 30 – Burlington	Eastern terminus of WYO 30
	​	349.45	562.39	WYO 36 (Golf Course Road)	Northern terminus of WYO 36
	Greybull	354.23	570.08	US 14 east (Greybull Avenue) – Shell, Sheridan	Southern end of US 14 concurrency
	​	359.21	578.09	US 14 / US 16 / US 20 west / US 310 begins – Cody, Yellowstone	Eastern terminus of US 310; northern end of US 14, US 16, and US 20 concurrencies; southern end of US 310 concurrency
	Lovell	386.24	621.59	US 14A east – Burgess Junction	Southern end of US 14A concurrency
	​	387.98	624.39	WYO 32 – Emblem	Northern terminus of WYO 32
	​	389.44	626.74	US 14A west – Byron, Powell, Cody	Northern end of US 14A concurrency
	Cowley	393.34	633.02	WYO 35	Northern terminus of WYO 35
	Deaver	399.35	642.69	WYO 114 – Garland, Powell, Cody	Eastern terminus of WYO 114
Park	​	407.14	655.23	US 310 east – Bridger, Billings	Continuation into Montana; northern end of US 310 concurrency
1.000 mi = 1.609 km; 1.000 km = 0.621 mi       Concurrency terminus

• U.S. Roads portal

• Wyoming Routes 500-789
• Wyoming Highway 789
• WYO 789 - US 310/Montana State Line to CO-13/Colorado State Line (see Wyoming 789)