Officially designated on August 24, 1924, the original route encompassed all of current SH-9 west of Blanchard. East of Blanchard, SH-9 followed a more northerly route. Bypassing Norman, SH-9 ran north to
Oklahoma City before going east through
Harrah,
Meeker,
Prague,
Henryetta, and
Checotah. The highway ended at the original
SH-3 in
Spiro. Upon the creation of the
United States Numbered Routes system in 1926, the section between Oklahoma City and Warner was overlaid with
US-266. Four years later in 1930, SH-9 was truncated to Chickasha. On 1935-08-27, the route was extended eastward, On 1937-08-25, the route was brought further east to end at US-69 in Eufaula. These sections were re-added on 1938-09-27. The final extension brought SH-9 to the Arkansas state line on 1941-11-12. Discussions to widen SH-9 to four lanes east of
US-77 in
Norman began in 2008. The City of Norman and ODOT have conflict in their proposals for the design of the widened highway. ODOT has proposed a paved median, with shoulders to accommodate bicyclists. Norman's proposal includes a grass median and a separate bike path along the north side of the right-of-way, running from 24th Avenue S.E. to
Lake Thunderbird. ODOT criticized the city's plan as too expensive. The city then proposed, with a narrower raised concrete median and separate bike path. By 2014, the plan for the widening had been finalized and work had begun from US 77 eastward. As of , SH-9 has been widened to four lanes to 108th Avenue S.E. Future plans call for the highway to be widened to four lanes from Pecan Creek to
SH-102. The
I-35 and SH-9 West interchange in
Goldsby was reconfigured into a
diverging diamond interchange in November 2025. The new design is expected to "accommodate large volumes of turning traffic by shifting traffic to the left side of a divided roadway through a series of coordinated signals for safer and more efficient left turns." This follows a large project that reconfigured the I-35 exit at West Lindsey Street into a
single point urban interchange and the SH-9 east exit to a
trumpet interchange in Norman. That project started in March 2015 and was completed and opened in October 2017. ==Junction list==