As John Tierney mentioned recently, and as Google's Michael Jones explained in an Atlantic interview last year ago, maps are both the most rapidly evolving and often the most useful ways to make sense of changes around us.
Two illustrations for the day. First, from a group called RTI, the "Synthetic Population Viewer," developed from Census data and originally intended to study disease and epidemiology patterns. That's a screen shot of one aspect of its map, above: it's greater Los Angeles, with differently colored dots representing the race of each household, against a black background. Below is how the Greenville-Greer-Spartanburg area looks, with a map background and a closer-in view. In both cases the red dots representing white households, turquoise representing black households, and others you can see online for other groupings :
Here's the comparable view of Washington DC and environs, which conveys one of the demographic realities of the area:
The maps can also show households differentiated by income, age, and household size -- or all four at once, in the "quad view." Among the interesting things about this approach (as Emily Badger described for Atlantic Cities last fall) is that each dot represents an individual household -- not a real, identifiable one but a "synthesized" but representative one derived from the data. You can read the background here and here and explore the map on your own here. It is much more configurable and open-ended than any screen shots can convey; I found it really fascinating.