Oklahoma County, Oklahoma Oklahoma County, Oklahoma Oklahoma County is a county located in the central part of the U.S. state of Oklahoma. As of the 2010 census, the population was 718,633, making it the most populous county in Oklahoma. The county seat is Oklahoma City, the state capital. Oklahoma County is at the heart of the Oklahoma City Metropolitan Statistical Area. Oklahoma County is one of seven counties in the United States to share the same name as the state it is located in (the other six counties are Arkansas County, Hawaii County, Idaho County, Iowa County, New York County (known commonly as
Oklahoma State Highway 23 the current western terminus of SH-15 was made with what was then Farm to Market Road 1265 to Booker and TX-117 back to Oklahoma.) The connection to Kansas north of US-64 did not exist as a state highway prior to 1957; it first appears on the 1958 state highway map, also signed as SH-15. The highway is not shown as overlapping US-64 and US-270 to Elmwood. SH-23 is first shown replacing SH-15 on the 1959 map, implying the change took place in 1958. Again, SH-23 is not shown as overlapping US-270; it would not be shown as doing such until