Revealing vertical geopolitics: Quantifying the volume of militarised restricted airspaces in the USA using GIS

Abstract The US military maintains significant control of land and sea territory, both domestically and internationally. Extending vertically, the US military also restricts vast areas of airspace to protect its interests in training, testing, surveillance, and security. In order to convey the multidimensional extent of spatial control maintained by the US Department of Defence, in this paper we critically assess, calculate, and depict the volume of militarised restricted airspaces in the USA. Airspace restrictions vary across days, times, and spatial extent, requiring an analysis and volumetric visualisation that can account for three‐ and four‐dimensional change. Applying this analysis casts the extent and variability of US military spatial control in fuller relief and makes visible new aspects of a vertical geopolitics. The research brings important new insights and methods to bear on little‐examined attributes of US militarisation and engages increasingly relevant questions about militarised airspace and contestable claims on near space.