|Length 379.7 km|
|South end: I-35 / US 77 at the Texas State Line|
North end: I-35 / Kansas Turnpike at the Kansas State Line
Oklahoma is the second state that Interstate 35 (I-35) passes through from south to north. In Oklahoma, I-35 runs from the Red River at the Texas border to the Kansas line near Braman, for a length of 236 miles (372 km). I-35 has one spur route in the state, Interstate 235 in the inner city of Oklahoma City.
Interstate 35 enters Oklahoma with U.S. Highway 77 on a bridge over the Red River in Love County, south of Thackerville. US-77 splits off at Exit 1, but parallels the interstate for its entire length in Oklahoma. I-35 maintains a near-due north–south course through Love and Carter Cos. I-35 provides four exits to Ardmore. After leaving Ardmore, it has a brief concurrency with State Highway 53 and enters Murray County and the Arbuckle Mountains. I-35 then passes through Garvin County and the county seat of Pauls Valley. North of exit 79, I-35 enters McClain County. There, it passes through Purcell and Goldsby.
State Highway 9 joins the interstate crossing over the South Canadian River into Cleveland County, after which it splits off again. It then serves as a major urban interstate in Norman and Moore. Between Norman and Moore, US-77 joins the interstate again. It then enters Oklahoma City and Oklahoma County near milepost 120. Near downtown, I-35 splits off the mainline (which becomes Interstate 235/US-77) and runs concurrent with Interstate 40 for a mile before splitting off to the north again. Interstate 44 then joins I-35 between mileposts 133 and 137. In Edmond US-77 joins the interstate yet again.
At milepost 146, I-35 enters Logan County. It serves Guthrie at Exit 153, where US-77 splits off, and at Exit 157. The interstate then crosses the Cimarron River into Payne County and enters Noble County shortly thereafter. It provides two exits to Perry and serves as the western terminus of the Cimarron Turnpike. After providing access to Tonkawa and Blackwell in Kay County, it crosses into Kansas, becoming the Kansas Turnpike.
Some sections of I-35 in Oklahoma City were already built in 1953, before the Interstate system was created. Following the passage of the Federal Highway Act of 1956 that created the Interstate Highway System, the Oklahoma Department of Transportation approved the location of the future interstate north of Oklahoma City to the Kansas state line on a route previously surveyed by the Oklahoma Turnpike Authority for a proposed toll road. As a free road, the first five miles (8 km) of that section of I-35 were opened to traffic in 1958 from US-177 near Braman north to the Kansas border where it continued as the Kansas Turnpike. This was followed by completion of the entire route from Oklahoma City northward to Braman by 1963 in several phases including Edmond to Guthrie in 1960, Guthrie to Perry in 1961, Perry to Blackwell in 1962 and Blackwell to Braman in early 1963.
To the south of Oklahoma City, I-35 was completed through Norman south to Purcell in June 1959. In Moore, it opened in two parts: the northern half, connecting Moore to Oklahoma City, opened in January 1960. The southern half, linking it to Norman, was opened to traffic in June 1967. The Moore–Norman segment was originally a four-lane section of US-77 built in 1951 that did not meet full Interstate Highway standards and included several at-grade intersections within the City of Moore including some with traffic signals and upgraded accordingly to include grade separations to bring up to full Interstate Highway standards and frontage roads to serve local traffic needs. Also not up to full Interstate Highway standards prior to 1967 was a section in the vicinity of Lindsey Street in the southern portion of Norman where another at-grade intersection still existed which dated back to the original highway's construction in the early 1950s—this was also brought up to full Interstate Highway standards in 1967 with the construction of interchanges on I-35 at Lindsey and a short distance to the south for the future SH-9 bypass that would be built around the south side of Norman in the early 1970s.
Further south, I-35 was completed from Marietta south to the Red River bridge in 1963, at which point a nearly 90-mile (140 km) gap of uncompleted interstate would exist between Purcell and Marietta until the late 1960s with traffic continuing to be routed over paralleling US-77. This was in large part due to efforts of the towns of Wynnewood, Paoli, and Wayne, fighting to keep I-35 as close as possible to US-77. This was successful due to a threat from Governor Henry Bellmon to build a toll road rather than I-35, and legislation preventing state funds for the interstate from being spent if it were more than 1-mile (1.6 km) from the U.S. route.
The uncompleted gap of I-35 in Southern Oklahoma was narrowed in 1967 and 1968 when two sections were completed from US-70/SH-199 in Ardmore south to SH-32 in Marietta. In 1969, the section of interstate bypassing Ardmore was completed north from US-70 two miles (3 km) to SH-142 and the following year, 1970, brought the completion of I-35 from SH-7 near Davis south to Ardmore, at long last bypassing the winding section of US-77 through the Arbuckle Mountains. This stretch through the Arbuckles was particularly expensive and difficult to construct, taking almost two years and requiring the blasting and removal of 4 million cubic yards of rock. A few months later in January, 1971, I-35 was finally completed across the state of Oklahoma, when the remaining portions of the interstate from Purcell to SH-7 near Davis were opened to traffic.
In 2008, the Oklahoma Department of Transportation announced plans to widen 2 miles (3.2 km) of Interstate 35 through Norman, from the Main Street interchange to the McCall Bridge over the South Canadian River (Exit 109). Controversy surrounding the project arose when early drafts eliminated the SH-74A/Lindsey Street interchange (Exit 108B), due to its proximity to the State Highway 9 interchange (Exit 108A). A public meeting held in Norman attracted 300 attendees, many bearing "Don't Close Lindsey" signs. Attendees cited the impact on local businesses and those attending University of Oklahoma football games as grounds for opposing the closure of the interchange. A former OU economics professor estimated the interchange's closure would cost Norman $100 million over the course of fifteen years.
At the meeting, four proposals were displayed, only one of which displayed no access from Lindsey Street. A second proposal would preserve access to Lindsey Street but require the seizure of a newly built Chevrolet dealership near the interchange. The third proposal would instead send the ramps around the dealership, and the fourth, the highest-cost alternate, would use bridges to prevent Lindsey Street and SH-9 traffic from conflicting. ODOT said their design standards did not require consideration of OU football traffic, because they only considered the 30th highest traffic percentile. One ODOT engineer was quoted as saying, "Otherwise, we'd have to 10-lane everything in Norman." In early 2011, a solution was unveiled that would retain access to Lindsey St. and reconstruct the interchange without displacing the dealership.
In 2014, ODOT completed reconstruction of the Main St. interchange as a Single Point Urban Interchange (SPUI) and widening of I-35 to just south of Main St. In early 2015, ODOT began a two-year, $71 million project to reconstruct the Lindsey St. interchange as a SPUI, reconstruct the SH-9 interchange and complete widening of I-35 to six lanes to the South Canadian River.
ODOT plans to reconstruct I-35/I-240 interchange in southeast Oklahoma City in several phases, the first beginning in 2016.