State Highway 66 (abbreviated SH-66) is a 192.7-mile (310.1 km) state highway in the U.S. state of Oklahoma, beginning at U.S. Highway 81 in El Reno and ending at U.S. Highway 60 near White Oak. The highway was designated in 1985 as a replacement for the decommissioned U.S. Highway 66. Although most of the highway follows Historic Route 66, the highway follows US 66's final alignment, joining Interstate 44 through Tulsa and Oklahoma City, while older versions of the route follow various city streets through both cities.

The highway has retained its importance for most of its length due to its paralleling Interstate 44 which between Missouri and Oklahoma City (except in the cities of Tulsa and Oklahoma City) is a toll road.

SH-66 currently has one spur route, designated SH-66B, in Wellston.

State Highway 66 begins at Business I-40 in El Reno (another old Route 66 segment), concurrent at this point with US-81. From this intersection, the highway heads due east. The highway briefly passes through a rural area after leaving El Reno, before transitioning into the Oklahoma City suburb of Yukon. In Yukon, the route runs along Main Street, and has a short concurrency with SH-4. SH-66 continues east, passing into Oklahoma City, where it becomes N.W. 39th Expressway. SH-66 has an interchange with the Kilpatrick Turnpike on the far west edge of the city. The highway passes just to the north of Lake Overholser. Near where the road crosses over the North Canadian River, the inlet to the lake, it crosses from Canadian County into Oklahoma County.

N.W. 39th Expressway, still carrying SH-66, forms the main street of both Bethany and Warr Acres, two enclave suburbs of Oklahoma City. The street passes just to the south of Wiley Post Airport and provides access to Southern Nazarene University. After leaving Warr Acres, the highway re-enters Oklahoma City. SH-66 leaves N.W. 39th Expressway at an interchange with I-44 and SH-3/SH-74 (the Lake Hefner Parkway). SH-66 begins a concurrency with eastbound I-44, and for the remainder of its length, it will stay close to the interstate.

SH-66 is unsigned through its time on the Oklahoma City freeway system. I-44, while concurrent with SH-66, runs along the north side of Oklahoma City, passing just south of Penn Square Mall, and meets Interstate 235 at a cloverleaf interchange at its northern terminus (north of the interchange, US-77 continues on as a freeway, the Broadway Extension). I-44 and SH-66 begin a concurrency with I-35 near Remington Park. The two interstates and the state highway head north through the northeast part of the city. At Hefner Road, the routes pass near the Frontier City amusement park. The highways then encounter an interchange which is the eastern terminus of the Kilpatrick Turnpike. This interchange is also where I-44 splits off to form the Turner Turnpike.

I-35 and SH-66 leave Oklahoma City and enter the suburb of Edmond. On the north side of town, SH-66 exits the interstate, while US-77 joins it. SH-66 continues east out of town, providing access to Arcadia Lake. The highway then passes through the town of Arcadia, home of the Round Barn, a Route 66 landmark. The highway then serves Luther before exiting Oklahoma County.

On the west side of Lincoln County, SH-66 produces a business loop to Wellston, SH-66B (below). Just beyond this junction, SH-66 serves as the northern terminus of SH-102. The highway continues east, meeting up again with SH-66B on the east side of Wellston. Near this junction, SH-66 has an interchange with the Turner Turnpike (still carrying I-44). The route continues to parallel the turnpike as it comes to an intersection with US-177. East of this junction, SH-66 passes through the town of Warwick, where it crosses the Deep Fork of the Canadian River.

On the southwest side of Chandler, the county seat of Lincoln County, the route is joined by SH-18. The two routes turn north, passing through the core of the downtown area. On the north side of downtown, SH-66 splits off to the east. Seven miles (11 km) east of Chandler, the highway passes through the town of Davenport. The route next encounters Stroud, where SH-66 intersects State Highway 99 and US-377, which may serve as the northern terminus of US-377.

East of Stroud, SH-66 passes into Creek County. The highway passes through the town of Depew 10 miles (16 km) northeast of Stroud. The route next passes through Bristow, where it has a brief concurrency with SH-16 and begins a more lengthy one with SH-48. SH-48/66 exit Bristow to the north, with an interchange where they cross the Turner Turnpike. Near unincorporated Bellvue, SH-66 splits away from SH-48 and turns back to the northeast. The highway crosses the Turner Turnpike again (with no interchange this time), then runs through Kellyville. Four miles (6.4 km) northeast of Kellyville, the highway begins a concurrency with SH-33. SH-33 and SH-66 will remain signed together as they enter the Tulsa metropolitan area.

SH-33/66 next enter Sapulpa, the county seat of Creek County and a suburb of Tulsa. In Sapulpa, the two highways serve as the western terminus of SH-117. They then come to the intersection of Dewey Avenue and Main Street in downtown Sapulpa, where SH-33 ends. This intersection also serves as the southern terminus of SH-97. SH-66 continues east through the intersection, joined by US-75 ALT. The two highways intersect SH-117A at its northern terminus, and turn left to continue its alignment. US-75 ALT/SH-66 parallel the Turner Turnpike within sight distance for the remainder of their journey in Creek County. Near the Creek–Tulsa County line, the Turner Turnpike ends, and SH-66 merges onto the now toll-free I-44. US-75 ALT ends at the merge.

I-44/SH-66 cut diagonally through the city of Tulsa. In West Tulsa, Interstate 244 branches off to serve the downtown area. I-44/SH-66 follow the Skelly Drive through midtown. The highways interchange with the Okmulgee Beeline, the US-75 freeway before crossing the Arkansas River. The next freeway interchange is with the Broken Arrow Expressway, carrying US-64 and SH-51, followed by the Mingo Valley Expressway, carrying US-169 I-244 then merges with I-44 at its eastern terminus. I-44/SH-66 cross into Rogers County and the suburb of Catoosa, serving as the southern terminus of SH-167. SH-66 then splits off from I-44, initially following an old alignment of the Interstate where it transitioned into the Will Rogers Turnpike. SH-66 then downgrades to an expressway as it passes through Catoosa, home of the Blue Whale. Northeast of Catoosa, near Verdigris, SH-66 intersects SH-266 at its eastern terminus.

The next town that SH-66 serves after leaving the Tulsa area is Claremore, seat of Rogers County. In Claremore, SH-66 has brief concurrencies with SH-20 and SH-88. The highway continues northeast through Rogers County, bypassing Sequoyah to the west and serving as the western terminus of SH-28A in Foyil. The highway passes through Bushyhead 2 miles (3.2 km) northeast of Foyil, and then intersect SH-28 in Chelsea 5 miles (8.0 km) further northeast. The route then crosses into Craig County, where it serves the unincorporated place of White Oak. The SH-66 designation then comes to an end at US-60, which Route 66 historically followed into Vinita.

The present-day SH-66 was established to fill the void left when US 66 was decommissioned through Oklahoma in the early 1980s. SH-66 was designated as its replacement from El Reno to White Oak on April 1, 1985. The remainder of US 66 in Oklahoma was overlapped by other highways, principally I-40 and US-69, so the SH-66 designation was not applied to these sections of highway.

On July 1, 1991, SH-66 was realigned in the vicinity of Luther. No further changes to the SH-66 designation have occurred since that time. Planned improvements by the Oklahoma Department of Transportation include reconstruction and widening of SH-66 from two to four lanes from Edmond to the Lincoln County line.

As part of a project to widen I-235 and US-77 to accommodate the increase amount of traffic, its interchange with I-44/SH-66 was reconstructed from a cloverleaf interchange to a four-level interchange that eliminated two cloverleaf ramps. The other two cloverleafs were widened and reconstructed and two new flyover ramps were added. The four-level interchange is the first of its kind in Oklahoma. The $105 million project lasted three years and was opened on March 3, 2022. An additional $16 million is being provided to reconstruct the I-44 to US-77 ramp and provide a direct connection to North Lincoln Boulevard. The project is expected to be started in 2023.

State Highway 66B
Location	Wellston
Length	3.26 mi (5.25 km)
Existed	June 26, 1934–present

While US 66 was still active, the SH-66 designation was given to a loop route through Wellston. This incarnation of SH-66 effectively served as a Wellston business loop for US 66. This route was first established on June 26, 1934. SH-66B is 3.26 miles (5.25 km) long.

County	Location	mi	km	Exit	Destinations	Notes
Canadian	El Reno	0.0	0.0		I-40 BL / US 81 to I-40 – Lucky Star Casino, Downtown, Lake, Golf Course, Sports Complex	Western terminus; road continues as I-40 Bus. west/US-81 north (former US 66 west)
	Yukon	11.0	17.7		SH-4 north (Cornwell Drive)	Western end of SH-4 concurrency
		11.2	18.0		SH-4 south (Ranchwood Boulevard)	Eastern end of SH-4 concurrency
	Oklahoma City	13.6	21.9		I-344 Toll (Kilpatrick Turnpike)	Interchange
Oklahoma		20.4	32.8	—	I-44 west / SH-3 – Lawton	Eastbound exit and westbound entrance; west end of freeway
				—	SH-3 west / SH-74 north (Lake Hefner Parkway)	Left exit eastbound; Lake Hefner Pkwy. exit 123B
				—	I-44 west to I-40 – Lawton, Amarillo	Western end of I-44 concurrency; I-44 exit 123B
				124	N. May Avenue	Exit numbers follow I-44
				125A	N. Penn Avenue	Full name is "Pennsylvania"
				125C	Northwest Expressway	No Eastbound exit
				125B	Classen Boulevard	No Westbound entrance
				126	Western Avenue	Westbound exits onto NW Grand Blvd
				127	I-235 / US 77 south – Oklahoma City, Downtown US 77 north (Broadway Extension) – Edmond	Split into exits 127A (south) and 127B (north) eastbound; westbound entrance includes direct entrance ramp from N. 63rd Street
				128A	Lincoln Boulevard – State Capitol
				128B	Kelley Avenue
				129	M.L. King Avenue
		27.6	44.4	130	I-35 west to I-40 – Oklahoma City, Dallas	Western end of I-35 concurrency; I-35 exit 133; no exit number westbound
				134	Wilshire Boulevard	Exit numbers follow I-35
				135	Britton Road
				136	Hefner Road
				137	NE 122nd Street
		32.2	51.8	138A	I-44 Toll east (Turner Turnpike) – Tulsa	Eastern end of I-44 concurrency
				138B	I-344 Toll west (Kilpatrick Turnpike)
				138C	Sooner Road	Westbound exit and eastbound entrance
	Edmond			138D	Memorial Road
				139	SE 33rd Street
				140	SE 15th Street
		35.8	57.6		I-35 / US 77 north – Wichita US 77 south (2nd Street west) – Edmond	Eastern end of I-35 concurrency; I-35 exit 141
Lincoln	​	55.2– 55.5	88.8– 89.3		SH-102 south / SH-66B east	Northern terminus of SH-102; western terminus of SH-66B; SH-66B was pre-1933 US-66 east
	Wellston	57.5	92.5		SH-66B west – Wellston	Pre-1933 US-66 west
	​	57.9	93.2		I-44 Toll / Turner Turnpike – Tulsa, Oklahoma City	I-44 exit 158
	Warwick	59.5	95.8		US 177 – Ponca City, Carney, Shawnee
	Chandler	67.3	108.3		SH-18 south – Shawnee, Meeker	western end of SH-18 concurrency
		68.2	109.8		SH-18 north (Manvel Avenue) to I-44 Toll – Cushing	eastern end of SH-18 concurrency
	Stroud	81.8	131.6		US 377 / SH-99 (8th Avenue) to I-44 Toll
Creek	Bristow	99.3	159.8		SH-16 east / SH-48 south (Main Street)	Western end of SH-16 / SH-48 concurrency
		100.0	160.9		SH-16 west – Shamrock	Eastern end of SH-16 concurrency
		100.5	161.7		I-44 Toll / Turner Turnpike – Tulsa, Oklahoma City	I-44 exit 196
	​	103.1	165.9		SH-48 north to SH-33	Eastern end of SH-48 concurrency
	Sapulpa	117.3	188.8		SH-33 west to I-44 Toll – Cushing	Western end of SH-33 concurrency
		120.2	193.4		SH-117 east	Western terminus of SH-117
		121.8	196.0		SH-33 ends / US 75 Alt. south (S. Main Street) / SH-97 north (N. Main Street)	Eastern end of SH-33 concurrency; eastern terminus of SH-33; southern terminus of SH-97; northern terminus of US-75 Alt.
		122.7	197.5		SH-117A south (Mission Street)	Northern terminus of SH-117A
		124.9	201.0		SH-364 / Creek Turnpike east	Interchange
Tulsa		128.7	207.1		I-44 Toll west / Turner Turnpike	Western end of I-44 concurrency, eastern terminus of Turner Tpk.; I-44 exit 221
				222A	49th West Avenue	Exit numbers follow I-44
				222B	55th Place	Eastbound exit only
				222C	56th Street	Westbound exit only
		129.9	209.1	223A	I-244 east (Red Fork Expressway) – Downtown Tulsa	Western terminus of I-244; I-244 exit 1A
				223B	51st Street	Access via Gilcrease Expressway; no eastbound exit
	Tulsa			223C	33rd West Avenue
				224	Union Avenue	C/D lanes provide access to US-75 and Elwood Ave.
		131.8	212.1		US 75 – Okmulgee, Bartlesville	Cloverleaf interchange; accessible to and from C/D lanes
				225	Elwood Avenue	Eastbound access is part of exit 224 accessible from C/D lanes originating at Union Ave. exit
				226A	Riverside Drive
				226B	Peoria Avenue
				227	Lewis Avenue
				228	51st Street / Harvard Avenue
				229	Yale Avenue
				230	41st Street / Sheridan Road
		138.5	222.9	231	US 64 / SH-51 to US 169 – Muskogee, Broken Arrow, Downtown Tulsa
				232	E. 31st Street / Memorial Drive	Eastbound exit is part of exit 231
				233	E. 21st Street	Signed as exit 233B westbound
		141.2	227.2	234A	US 169 – Owasso, Broken Arrow	No eastbound exit to US-169 south
				234B	Garnett Road	Eastbound exit and westbound entrance
				235	E. 11th Street
				236	129th East Avenue
		144.0	231.7	236B	I-244 / US 412 west (Crosstown Expressway) – Sand Springs, Enid	Westbound exit and eastbound entrance; western end of US-412 concurrency; eastern terminus of I-244
Tulsa–Rogers county line	Tulsa–Catoosa line			238	161st East Avenue
				240	SH-167 north (193rd East Avenue)	No eastbound entrance
	Catoosa	147.7	237.7	—	I-44 / US 412 east – Claremore, Joplin, Chouteau, Siloam Springs	East end of freeway section; no westbound access to I-44/US-412 east; eastern end of I-44/US-412 concurrency; former SH-33 east; I-44 east exit 241
Rogers				—	I-44 Toll / Will Rogers Turnpike east – Claremore, Joplin	Former tolled interchange; closed upon I-44/Will Rogers Tpk. realignment; had no eastbound exit; former Will Rogers Tpk. exit 241
	Verdigris	155.4	250.1		SH-266 to I-44 Toll (Turnpike) – Port of Catoosa	Interchange
	Claremore	160.9	258.9		SH-88 south (First Street)	western end of SH-88 concurrency
		161.0	259.1		SH-20 east (Patti Page Boulevard)	western end of SH-20 concurrency
		161.0	259.1		SH-20 west / SH-88 north (Will Rogers Boulevard)	eastern end of SH-20 / SH-88 concurrency
	Foyil	171.4	275.8		SH-28A east – Adair	Western terminus of SH-28A
	Chelsea	179.0	288.1		SH-28 east – Adair	Western end of SH-28 concurrency
		179.6	289.0		SH-28 west (6th Street) – Alluwe	Eastern end of SH-28 concurrency
Craig	​	192.7	310.1		US 60 east	Eastern terminus; no direct access to US-60 west; road continues as US-60 east (former US 66 east)
1.000 mi = 1.609 km; 1.000 km = 0.621 mi       Closed/former       Concurrency terminus       Incomplete access        Tolled

• U.S. Route 66
• U.S. Route 66 in Oklahoma
• K-66

• SH-66 at OKHighways