We're moving farther and farther west, plus a little south

Yes, the 1800s were the age of westward expansion, but the trend never really stopped. One way the Census Bureau measures geographic shifts is by measuring the US's "mean center of population" — that is, "the place where an imaginary, flat, weightless and rigid map of the United States would balance perfectly" if all Americans weighed exactly the same. As of 2010, that point was near the village of Plato, Missouri. But this westward and southward doesn't necessarily mean that lots of Americans are packing up and moving west and south...rather, it simply means that the populations of the West and South keep growing faster than the Northeast and Midwest. That includes people moving, but also shifts in birth rates and immigration.