The phrase "adjacent state" is correct and usable in written English.
It can be used to refer to a state that is next to or neighboring another state, often in geographical or political contexts.
Example: "The adjacent state of New York has a diverse population and vibrant culture."
Alternatives: "neighboring state" or "contiguous state".
Fortunately, the Violent Femmes bassist was from the adjacent state to the murder suspect.
Highlands Montana has drilled a few test wells on adjacent state land it has leased here.
The package comes with an additional $18 million to build an adjacent state history museum.
The provision would have given the governor "of the adjacent state," Massachusetts, veto power over any such installation.
The measure, an amendment to a Coast Guard budget bill, gives the governor of "the adjacent state," Massachusetts, veto power over any wind farm in the sound.
The species is partially migratory, moving north in winter, at which season it also, at least periodically, reaches the adjacent state of Santa Catarina.
Like Steamtown, whose train-buff visitors often spill over to the Lackawanna site and the adjacent state-run Anthracite Heritage Museum, the mine tour emphasizes the real thing.
The suit, filed in United States District Court in Houston, said the company, which obtained permission from the state in the 1970's to drill on a parcel of land called Hawkins Field in Wood County in eastern Texas, had strayed onto adjacent state-owned land not covered by its permits.
Charcoal and fuelwood were mostly obtained from the adjacent state-owned forests.
Indeed, since the Sultanate's demise, Soqotran pastoralists did not have to resist the state as it was chronically absent in their pastoral domain, but the pastoralists sought to participate opportunistically in the territorially adjacent state-sponsored economy on the coast to sustain their pastoral economy.
The Harvard-owned property and the adjacent state-owned Lowell Park were declared a National Historic Landmark District in 1966.
