Canada.
To the north Montana borders Canadian provinces British Columbia, Alberta, and Saskatchewan.
The country you seek is Canada.
Oklahoma shares most of Texas's northern border.
The state that shares a northern border with South Dakota is Nebraska. The capital of Nebraska is Lincoln.
Finland
Mexico
The area that shares a border with Sudan.
Kansas
There is no Australian state which shares a border with all other states. No state except for Victoria shares a land border with Tasmania. South Australia shares a border with all mainland states and the Northern Territory.
New Mexico''s northern border is shared with Colorado.
Mongolia, on China's northern border, shares the Gobi Desert.
nepal
china