I hate, hate, HATE this. It implies the main land-use is the only use. Do people in the Midwest simply commute 2,000 miles a day, since that's where the housing is? This belongs in c/UglyInaccurateData...
It seems you're misunderstanding the map. It's how much space each of those categories is taking up as a fraction of the total area of the contiguous US, not where that land use primarily occurs.