On the NPR blog, Robert Krullwich noticed that pictures taken at night from space of the US show a recent phenomenon — one of the brightest patches is in one of the least populated places in the US — western North Dakota.
The reason, apparently, is the boom in oil drilling. In addition to the lighting that the drillers bring with them, the drilling makes extensive use of the practice of burning off natural gas. Those flares have turned this relatively underpopulated area into an area as bright as major metropolitan areas, such as Minneapolis-St.Paul.
You can find the NPR article here.