The Red River is the boundary.
Red river
The Red River forms Oklahoma's southern border with Texas.
Bordering Texas and Louisiana is the Sabine River, the Red River borders Texas and Oklahoma, and between Texas and New Mexico/Mexico is the Rio.
The River that forms a border between Oklahoma and Texas is the Red River. The river was named for the red-bed country of its watershed.
Lake Texoma
It is approximately 500 miles from Brownsville, Texas to the Oklahoma border.
the red river is the intended answer but technically only the vegetation line on its right bank forms the border the river itself is entirely within Oklahoma everywhere between the Texas panhandle & Arkansas
Marlow is about 52.5 miles from the Oklahoma/Texas border.
The Texas-Oklahoma state boundary is approximately 540 miles long.
Texas is the only state to border Oklahoma to the south.
Oklahoma shares most of Texas's northern border.
No, it is not. Texas and Oklahoma are neighboring states of the United States, and they are not the same. Oklahoma does share a border with Texas; there is also a Texas County in Oklahoma. But when you are talking about Texas, you are talking about a separate state, which is not part of Oklahoma at all.
The North of Texas and the South of Oklahoma share a common border. The East side of the Texas panhandle also shares a border with the western side of Oklahoma beneath the Oklahoma panhandle.