SH-20 begins just north of the
Arkansas River at SH-18 near Ralston. From there, it heads east through
Osage County for 20 miles (32 km) without crossing any other highway. At mile 20.4, it meets
State Highway 99 in
Hominy. East of Hominy, SH-20 crosses
Lake Skiatook before passing through
Skiatook and entering
Tulsa County. Shortly after entering Tulsa County, SH-20 has a junction with
SH-11. Four miles later, it has an interchange with
US-75. After running through
Collinsville, it turns southward onto the
US-169 freeway. SH-20 splits from US-169 north of
Owasso. It then enters
Claremore, where it meets
SH-88 and
SH-66 (old Route 66). It connects to the Claremore
toll plaza on
I-44/
Will Rogers Turnpike. East of Claremore, SH-20 becomes a divided expressway before intersecting
US-69 in
Pryor. West of
Salina, the highway bridges
Lake Hudson. In Salina, SH-20 meets
SH-82, with which it begins a concurrency. Headed north from Salina, the two highways begin to cross some mountainous terrain. The highways provide access to
Spavinaw State Park, before running through the town of
Spavinaw, Oklahoma. North of Spavinaw, SH-20 splits off to the east, running through unincorporated
Chloeta and serving as the eastern terminus of
SH-28. SH-20 overlaps
US-59/
State Highway 10 through
Jay. SH-20 then splits off to the east, running to the Arkansas line. The easternmost miles run north/south along the Oklahoma–Arkansas state line, and along this stretch the highway
overlaps Arkansas's
Highway 43. The highway continues northward into Missouri at the point where the Oklahoma, Arkansas and Missouri borders meet, and thereafter becomes
Missouri Route 43. ==History==