The US Air Force intends to increase the airspace at its Powder River Training Complex in Dakota for training exercises with B-1 and B-52 bombers.
The air force is drafting a proposal to ask the Federal Aviation Administration to add three military operation areas to create a fly space of about 25,000 square miles.
The expanded area will help pilots practice bomb runs, defensive manoeuvres and evasive actions used in Iraq and Afghanistan, according to the Associated Press.
The air force can also conduct larger-scale training exercises in the space, although they would be limited to no more than one every three months.
Ellsworth's airspace manager George Stone said the existing airspace can accommodate only one or two bombers at a time, so bombers from South Dakota's Ellsworth Air Force Base and North Dakota's Minot Air Force Base have to fly to Nevada for their combat exercises.
The air force is also drafting a environmental impact statement for the expansion. The plan has raised concern among local ranchers about the safety of their property and cattle.