In Eastern Colorado, the human tide ebbs. Cheyenne county, which had 3,700 inhabitants in 1930, now has just 1,900. And the drift away from the area seems to be speeding up. In the old county jail, which is now a museum, a photograph from 1910 shows a three-storey schoolhouse towering over the town of Cheyenne Wells. The new school is one storey high-yet it already seems too big. America as a whole is growing briskly. Between 2000 and 2006 its population swelled by 6.4%, according to the Census Bureau. Yet the expansion has passed many areas by. Two-fifths of all counties are shrinking (see map). In general, people are moving to places that are warm, mountainous or suburban. They are leaving many rural areas, with the most relentless decline in a broad band stretching from western Texas to North Dakota. In parts, the Great Plains are more sparsely populated now than they were in the late 19th century, when the government declared them to be deserted. A big reason is improvements in farming technology. Tractors in eastern Colorado do not resemble the vehicles that trundle around farms on the east coast and in Europe. They are many-wheeled monsters, […]