See more maps by Kaitlin Duck Sherwood, my future plans, and credits.
The darker the red, the higher the value. "% White" is on a linear 30-100% scale -- any tract with less than 30% white will show as full white. All the other races are on a linear 0-70% scale -- any tract with more than 70% will show as full red. Density is on a linear 0-10,000 scale. Note that some urban areas can have densities in the 100,000 range.
I don't draw borders on the tracts that only take up a few pixels. That's why urban regions tend to have a ring around them with no borders.
NOTE: when you are looking at census data, the farthest you can zoom out is to see roughly 2/3 of the US at once. (At some point, I'll make the tiles for farther-zoomed out, but not right away.) In the other direction, Google added a few more zoom levels in API v.2 that my tile server doesn't know about. It usually isn't interesting to zoom in that far, so fixing that isn't a priority for me. You will have a better experience if you clear your browser's cache before doing much.How can I save a map view to look at later?
How can I go to a particular address?
How can I make the response faster?
Why don't I see much color variation in my percentage figures?
Why can't I zoom all the way out?
Why is there a horizontal line sometimes?
Are there census overlays for Google Earth?
Is the author looking for a job?